Setting search (#41285)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request

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## PR Checklist

- [ ] Closes: #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [x] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
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- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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## Validation Steps Performed
Localized search:
<img width="1576" height="480" alt="image"
src="https://github.com/user-attachments/assets/dd6e5e9f-419b-40b1-b796-f0799481ecfc"
/>


## AI summary
This pull request introduces infrastructure and code to support search
functionality for PowerToys settings, including a new search index
specification, a dedicated search library, and updates to the solution
configuration. The main changes are the addition of a spec describing
how settings should be indexed and navigated, the creation of a new
`Common.Search` project with a fuzz search implementation, and updates
to the solution file to include these new components.

**Settings Search Feature Implementation**

* Documentation:
* Added a detailed specification (`settings-search.md`) describing the
structure of PowerToys settings pages, how to index settings, navigation
logic, runtime search, result grouping, build-time indexing strategy,
and corner cases.

* New Search Library:
* Added the new `Common.Search` project to the solution, including its
project file and implementation of a fuzz search service
(`FuzzSearchService<T>`), match options, match results, and search
precision scoring.
[[1]](diffhunk://#diff-ddc06fa41e4e723e54181b0cb85cdd00f57f75725d51ceefa242d4d651a9a363R1-R8)
[[2]](diffhunk://#diff-1a2ca29fc33bcccf338a7843a040ca2c31ba821e8cab7064fab0dbb1224d454cR1-R39)
[[3]](diffhunk://#diff-242764d948b795f39653a84d9b6bfcdc52730100deab2e3a0995be95bb8e7868R1-R10)
[[4]](diffhunk://#diff-61e525491ed916ebd65dabb66dd4f5dc720320d7e295ef1e0bd6d506ea0f7df6R1-R67)
[[5]](diffhunk://#diff-a775f6de2e8d42982829b4161668f49dedbbd9dcbb05ce20003de7e62275c57aR1-R12)

* Solution Configuration:
* Updated `PowerToys.sln` to include `Common.Search` and
`Settings.UI.XamlIndexBuilder` projects, and configured their build
settings for various platforms and mapped project dependencies.
[[1]](diffhunk://#diff-ca837ce490070b91656ffffe31cbad8865ba9174e0f020231f77baf35ff3f811R714-R716)
[[2]](diffhunk://#diff-ca837ce490070b91656ffffe31cbad8865ba9174e0f020231f77baf35ff3f811R2704-R2727)
[[3]](diffhunk://#diff-ca837ce490070b91656ffffe31cbad8865ba9174e0f020231f77baf35ff3f811R2889)
[[4]](diffhunk://#diff-ca837ce490070b91656ffffe31cbad8865ba9174e0f020231f77baf35ff3f811R3157-R3158)

**Spell-check Dictionary Updates**

* Added new terms related to navigation and settings UI components (such
as `Navigatable`, `NavigatablePage`, `settingscard`, `Tru`, `tweakable`)
to the spell-check dictionary to support the new search and indexing
features.
[[1]](diffhunk://#diff-5dcab162c1b233a49973ae010f2b88c7ec4844382abd705e6154685e62bd5c4dR1020-R1021)
[[2]](diffhunk://#diff-5dcab162c1b233a49973ae010f2b88c7ec4844382abd705e6154685e62bd5c4dR1498)
[[3]](diffhunk://#diff-5dcab162c1b233a49973ae010f2b88c7ec4844382abd705e6154685e62bd5c4dR1755-R1761)

---------

Co-authored-by: Niels Laute <niels.laute@live.nl>
Co-authored-by: Gordon Lam (SH) <yeelam@microsoft.com>
Co-authored-by: Gordon Lam <73506701+yeelam-gordon@users.noreply.github.com>

src/settings-ui/Settings.UI/ViewModels/SearchResultsViewModel.cs

@@ -0,0 +1,133 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using Microsoft.PowerToys.Settings.UI.Services;
+using Settings.UI.Library;
+
+namespace Microsoft.PowerToys.Settings.UI.ViewModels
+{
+    public class SearchResultsViewModel : INotifyPropertyChanged
+    {
+        private ObservableCollection<SettingEntry> _moduleResults = new();
+        private ObservableCollection<SettingsGroup> _groupedSettingsResults = new();
+        private bool _hasNoResults;
+
+        public ObservableCollection<SettingEntry> ModuleResults
+        {
+            get => _moduleResults;
+            set
+            {
+                _moduleResults = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public ObservableCollection<SettingsGroup> GroupedSettingsResults
+        {
+            get => _groupedSettingsResults;
+            set
+            {
+                _groupedSettingsResults = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public bool HasNoResults
+        {
+            get => _hasNoResults;
+            set
+            {
+                _hasNoResults = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public void SetSearchResults(string query, List<SettingEntry> results)
+        {
+            if (results == null || results.Count == 0)
+            {
+                HasNoResults = true;
+                ModuleResults.Clear();
+                GroupedSettingsResults.Clear();
+                return;
+            }
+
+            HasNoResults = false;
+
+            // Separate modules and settings
+            var modules = results.Where(r => r.Type == EntryType.SettingsPage).ToList();
+            var settings = results.Where(r => r.Type == EntryType.SettingsCard).ToList();
+
+            // Update module results
+            ModuleResults.Clear();
+            foreach (var module in modules)
+            {
+                ModuleResults.Add(module);
+            }
+
+            // Group settings by their page/module
+            var groupedSettings = settings
+                .GroupBy(s => SearchIndexService.GetLocalizedPageName(s.PageTypeName))
+                .Select(g => new SettingsGroup
+                {
+                    GroupName = g.Key,
+                    Settings = new ObservableCollection<SettingEntry>(g),
+                })
+                .ToList();
+
+            GroupedSettingsResults.Clear();
+            foreach (var group in groupedSettings)
+            {
+                GroupedSettingsResults.Add(group);
+            }
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+
+#pragma warning disable SA1402 // File may only contain a single type
+    public class SettingsGroup : INotifyPropertyChanged
+#pragma warning restore SA1402 // File may only contain a single type
+    {
+        private string _groupName;
+        private ObservableCollection<SettingEntry> _settings;
+
+        public string GroupName
+        {
+            get => _groupName;
+            set
+            {
+                _groupName = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public ObservableCollection<SettingEntry> Settings
+        {
+            get => _settings;
+            set
+            {
+                _settings = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}

src/settings-ui/Settings.UI/ViewModels/ShellViewModel.cs

@@ -32,9 +32,11 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
         private IList<KeyboardAccelerator> keyboardAccelerators;
         private NavigationView navigationView;
         private NavigationViewItem selected;
+        private NavigationViewItem expanding;
         private ICommand loadedCommand;
         private ICommand itemInvokedCommand;
         private NavigationViewItem[] _fullListOfNavViewItems;
+        private NavigationViewItem[] _moduleNavViewItems;
         private GeneralSettings _generalSettingsConfig;
 
         public bool IsBackEnabled
@@ -55,6 +57,17 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
             set => Set(ref selected, value);
         }
 
+        public NavigationViewItem Expanding
+        {
+            get { return expanding; }
+            set { Set(ref expanding, value); }
+        }
+
+        public NavigationViewItem[] NavItems
+        {
+            get { return _moduleNavViewItems; }
+        }
+
         public ICommand LoadedCommand => loadedCommand ?? (loadedCommand = new RelayCommand(OnLoaded));
 
         public ICommand ItemInvokedCommand => itemInvokedCommand ?? (itemInvokedCommand = new RelayCommand<NavigationViewItemInvokedEventArgs>(OnItemInvoked));
@@ -74,7 +87,8 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
             NavigationService.Navigated += Frame_Navigated;
             this.navigationView.BackRequested += OnBackRequested;
             var topLevelItems = navigationView.MenuItems.OfType<NavigationViewItem>();
-            _fullListOfNavViewItems = topLevelItems.Union(topLevelItems.SelectMany(menuItem => menuItem.MenuItems.OfType<NavigationViewItem>())).ToArray();
+            _moduleNavViewItems = topLevelItems.SelectMany(menuItem => menuItem.MenuItems.OfType<NavigationViewItem>()).ToArray();
+            _fullListOfNavViewItems = topLevelItems.Union(_moduleNavViewItems).ToArray();
         }
 
         private static KeyboardAccelerator BuildKeyboardAccelerator(VirtualKey key, VirtualKeyModifiers? modifiers = null)

src/settings-ui/Settings.UI/ViewModels/SuggestionItem.cs

@@ -0,0 +1,25 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.PowerToys.Settings.UI.ViewModels
+{
+    public sealed partial class SuggestionItem
+    {
+        public string Header { get; init; }
+
+        public string Icon { get; init; }
+
+        public string PageTypeName { get; init; }
+
+        public string ElementName { get; init; }
+
+        public string ParentElementName { get; init; }
+
+        public string Subtitle { get; init; }
+
+        public bool IsShowAll { get; init; }
+
+        public bool IsNoResults { get; init; }
+    }
+}