CmdPal: Extract persistence services from SettingsModel and AppStateModel (#46312)

## Summary of the Pull Request

Extracts persistence (load/save) logic from `SettingsModel` and
`AppStateModel` into dedicated service classes, following the
single-responsibility principle. Consumers now interact with
`ISettingsService` and `IAppStateService` instead of receiving raw model
objects through DI.

**New services introduced:**
- `IPersistenceService` / `PersistenceService` — generic `Load<T>` /
`Save<T>` with AOT-compatible `JsonTypeInfo<T>`, ensures target
directory exists before writing
- `ISettingsService` / `SettingsService` — loads settings on
construction, runs migrations, exposes `Settings` property and
`SettingsChanged` event
- `IAppStateService` / `AppStateService` — loads state on construction,
exposes `State` property and `StateChanged` event

**Key changes:**
- `SettingsModel` and `AppStateModel` are now pure data models — all
file I/O, migration, and directory management removed
- Raw `SettingsModel` and `AppStateModel` removed from DI container;
consumers receive the appropriate service
- `IApplicationInfoService.ConfigDirectory` injected into services for
config path resolution (no more hardcoded `Utilities.BaseSettingsPath`)
- ~30 consumer files updated across `Microsoft.CmdPal.UI.ViewModels` and
`Microsoft.CmdPal.UI` projects
- All `#pragma warning disable SA1300` suppressions removed —
convenience accessors replaced with direct `_settingsService.Settings` /
`_appStateService.State` access
- Namespace prefixes (`Services.ISettingsService`) replaced with proper
`using` directives

## PR Checklist

- [ ] **Communication:** I've discussed this with core contributors
already.
- [x] **Tests:** Added/updated and all pass
- [ ] **Localization:** N/A — no end-user-facing strings changed
- [ ] **Dev docs:** N/A — internal refactor, no public API changes
- [ ] **New binaries:** N/A — no new binaries introduced

## Detailed Description of the Pull Request / Additional comments

### Architecture

Services are registered as singletons in `App.xaml.cs`:
```csharp
services.AddSingleton<IPersistenceService, PersistenceService>();
services.AddSingleton<ISettingsService, SettingsService>();
services.AddSingleton<IAppStateService, AppStateService>();
```

`PersistenceService.Save<T>` writes the serialized model directly to
disk, creating the target directory if it doesn't exist. It also does
not attempt to merge existing and new settings/state. `SettingsService`
runs hotkey migrations on load and raises `SettingsChanged` after saves.
`AppStateService` always raises `StateChanged` after saves.

### Files changed (41 files, +1169/−660)

| Area | Files | What changed |
|------|-------|-------------|
| New services | `Services/IPersistenceService.cs`,
`PersistenceService.cs`, `ISettingsService.cs`, `SettingsService.cs`,
`IAppStateService.cs`, `AppStateService.cs` | New service interfaces and
implementations |
| Models | `SettingsModel.cs`, `AppStateModel.cs` | Stripped to pure
data bags |
| DI | `App.xaml.cs` | Service registration, removed raw model DI |
| ViewModels | 12 files | Constructor injection of services |
| UI | 10 files | Service injection replacing model access |
| Settings | `DockSettings.cs` | `Colors.Transparent` replaced with
struct literal to avoid WinUI3 COM dependency |
| Tests | `PersistenceServiceTests.cs`, `SettingsServiceTests.cs`,
`AppStateServiceTests.cs` | 38 unit tests covering all three services |
| Config | `.gitignore` | Added `.squad/`, `.github/agents/` exclusions
|

## Validation Steps Performed

- Built `Microsoft.CmdPal.UI` with MSBuild (x64/Debug) — exit code 0,
clean build
- Ran 38 unit tests via `vstest.console.exe` — all passing
- Verified no remaining `#pragma warning disable SA1300` blocks
- Verified no remaining `Services.` namespace prefixes

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Commands/MainListPage.cs

@@ -18,6 +18,7 @@ using Microsoft.CmdPal.Ext.Apps.Programs;
 using Microsoft.CmdPal.UI.ViewModels.Commands;
 using Microsoft.CmdPal.UI.ViewModels.Messages;
 using Microsoft.CmdPal.UI.ViewModels.Properties;
+using Microsoft.CmdPal.UI.ViewModels.Services;
 using Microsoft.CommandPalette.Extensions;
 using Microsoft.CommandPalette.Extensions.Toolkit;
 
@@ -42,8 +43,8 @@ public sealed partial class MainListPage : DynamicListPage,
     private readonly ThrottledDebouncedAction _refreshThrottledDebouncedAction;
     private readonly TopLevelCommandManager _tlcManager;
     private readonly AliasManager _aliasManager;
-    private readonly SettingsModel _settings;
-    private readonly AppStateModel _appStateModel;
+    private readonly ISettingsService _settingsService;
+    private readonly IAppStateService _appStateService;
     private readonly ScoringFunction<IListItem> _scoringFunction;
     private readonly ScoringFunction<IListItem> _fallbackScoringFunction;
     private readonly IFuzzyMatcherProvider _fuzzyMatcherProvider;
@@ -79,23 +80,23 @@ public sealed partial class MainListPage : DynamicListPage,
 
     public MainListPage(
         TopLevelCommandManager topLevelCommandManager,
-        SettingsModel settings,
         AliasManager aliasManager,
-        AppStateModel appStateModel,
-        IFuzzyMatcherProvider fuzzyMatcherProvider)
+        IFuzzyMatcherProvider fuzzyMatcherProvider,
+        ISettingsService settingsService,
+        IAppStateService appStateService)
     {
         Id = "com.microsoft.cmdpal.home";
         Title = Resources.builtin_home_name;
         Icon = IconHelpers.FromRelativePath("Assets\\Square44x44Logo.altform-unplated_targetsize-256.png");
         PlaceholderText = Properties.Resources.builtin_main_list_page_searchbar_placeholder;
 
-        _settings = settings;
+        _settingsService = settingsService;
         _aliasManager = aliasManager;
-        _appStateModel = appStateModel;
+        _appStateService = appStateService;
         _tlcManager = topLevelCommandManager;
         _fuzzyMatcherProvider = fuzzyMatcherProvider;
-        _scoringFunction = (in query, item) => ScoreTopLevelItem(in query, item, _appStateModel.RecentCommands, _fuzzyMatcherProvider.Current);
-        _fallbackScoringFunction = (in _, item) => ScoreFallbackItem(item, _settings.FallbackRanks);
+        _scoringFunction = (in query, item) => ScoreTopLevelItem(in query, item, _appStateService.State.RecentCommands, _fuzzyMatcherProvider.Current);
+        _fallbackScoringFunction = (in _, item) => ScoreFallbackItem(item, _settingsService.Settings.FallbackRanks);
 
         _tlcManager.PropertyChanged += TlcManager_PropertyChanged;
         _tlcManager.TopLevelCommands.CollectionChanged += Commands_CollectionChanged;
@@ -150,8 +151,8 @@ public sealed partial class MainListPage : DynamicListPage,
         WeakReferenceMessenger.Default.Register<ClearSearchMessage>(this);
         WeakReferenceMessenger.Default.Register<UpdateFallbackItemsMessage>(this);
 
-        settings.SettingsChanged += SettingsChangedHandler;
-        HotReloadSettings(settings);
+        _settingsService.SettingsChanged += SettingsChangedHandler;
+        HotReloadSettings(_settingsService.Settings);
         _includeApps = _tlcManager.IsProviderActive(AllAppsCommandProvider.WellKnownId);
 
         IsLoading = true;
@@ -364,7 +365,7 @@ public sealed partial class MainListPage : DynamicListPage,
             }
 
             // prefilter fallbacks
-            var globalFallbacks = _settings.GetGlobalFallbacks();
+            var globalFallbacks = _settingsService.Settings.GetGlobalFallbacks();
             var specialFallbacks = new List<TopLevelViewModel>(globalFallbacks.Length);
             var commonFallbacks = new List<TopLevelViewModel>(commands.Count - globalFallbacks.Length);
 
@@ -479,7 +480,7 @@ public sealed partial class MainListPage : DynamicListPage,
 
                     // We need to remove pinned apps from allNewApps so they don't show twice.
                     // Pinned app command IDs are stored in ProviderSettings.PinnedCommandIds.
-                    _settings.ProviderSettings.TryGetValue(AllAppsCommandProvider.WellKnownId, out var providerSettings);
+                    _settingsService.Settings.ProviderSettings.TryGetValue(AllAppsCommandProvider.WellKnownId, out var providerSettings);
                     var pinnedCommandIds = providerSettings?.PinnedCommandIds;
 
                     if (pinnedCommandIds is not null && pinnedCommandIds.Count > 0)
@@ -678,9 +679,9 @@ public sealed partial class MainListPage : DynamicListPage,
     public void UpdateHistory(IListItem topLevelOrAppItem)
     {
         var id = IdForTopLevelOrAppItem(topLevelOrAppItem);
-        var history = _appStateModel.RecentCommands;
+        var history = _appStateService.State.RecentCommands;
         history.AddHistoryItem(id);
-        AppStateModel.SaveState(_appStateModel);
+        _appStateService.Save();
     }
 
     private static string IdForTopLevelOrAppItem(IListItem topLevelOrAppItem)
@@ -703,7 +704,7 @@ public sealed partial class MainListPage : DynamicListPage,
         RequestRefresh(fullRefresh: false);
     }
 
-    private void SettingsChangedHandler(SettingsModel sender, object? args) => HotReloadSettings(sender);
+    private void SettingsChangedHandler(ISettingsService sender, SettingsModel args) => HotReloadSettings(args);
 
     private void HotReloadSettings(SettingsModel settings) => ShowDetails = settings.ShowAppDetails;
 
@@ -716,9 +717,9 @@ public sealed partial class MainListPage : DynamicListPage,
         _tlcManager.PropertyChanged -= TlcManager_PropertyChanged;
         _tlcManager.TopLevelCommands.CollectionChanged -= Commands_CollectionChanged;
 
-        if (_settings is not null)
+        if (_settingsService is not null)
         {
-            _settings.SettingsChanged -= SettingsChangedHandler;
+            _settingsService.SettingsChanged -= SettingsChangedHandler;
         }
 
         WeakReferenceMessenger.Default.UnregisterAll(this);