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/CommandPaletteContextMenuFactory.cs

@@ -6,6 +6,7 @@ using CommunityToolkit.Mvvm.Messaging;
 using ManagedCommon;
 using Microsoft.CmdPal.UI.ViewModels;
 using Microsoft.CmdPal.UI.ViewModels.Messages;
+using Microsoft.CmdPal.UI.ViewModels.Services;
 using Microsoft.CmdPal.UI.ViewModels.Settings;
 using Microsoft.CommandPalette.Extensions;
 using Microsoft.CommandPalette.Extensions.Toolkit;
@@ -15,12 +16,12 @@ namespace Microsoft.CmdPal.UI;
 
 internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFactory
 {
-    private readonly SettingsModel _settingsModel;
+    private readonly ISettingsService _settingsService;
     private readonly TopLevelCommandManager _topLevelCommandManager;
 
-    public CommandPaletteContextMenuFactory(SettingsModel settingsModel, TopLevelCommandManager topLevelCommandManager)
+    public CommandPaletteContextMenuFactory(ISettingsService settingsService, TopLevelCommandManager topLevelCommandManager)
     {
-        _settingsModel = settingsModel;
+        _settingsService = settingsService;
         _topLevelCommandManager = topLevelCommandManager;
     }
 
@@ -65,7 +66,7 @@ internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFac
             var providerId = providerContext.ProviderId;
             if (_topLevelCommandManager.LookupProvider(providerId) is CommandProviderWrapper provider)
             {
-                var providerSettings = _settingsModel.GetProviderSettings(provider);
+                var providerSettings = _settingsService.Settings.GetProviderSettings(provider);
 
                 var alreadyPinnedToTopLevel = providerSettings.PinnedCommandIds.Contains(itemId);
 
@@ -82,7 +83,7 @@ internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFac
                         providerId: providerId,
                         pin: !alreadyPinnedToTopLevel,
                         PinLocation.TopLevel,
-                        _settingsModel,
+                        _settingsService,
                         _topLevelCommandManager);
 
                     var contextItem = new PinToContextItem(pinToTopLevelCommand, commandItem);
@@ -132,7 +133,7 @@ internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFac
         var providerId = providerContext.ProviderId;
         if (_topLevelCommandManager.LookupProvider(providerId) is CommandProviderWrapper provider)
         {
-            var providerSettings = _settingsModel.GetProviderSettings(provider);
+            var providerSettings = _settingsService.Settings.GetProviderSettings(provider);
 
             var isPinnedSubCommand = providerSettings.PinnedCommandIds.Contains(itemId);
             if (isPinnedSubCommand)
@@ -142,7 +143,7 @@ internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFac
                        providerId: providerId,
                        pin: !isPinnedSubCommand,
                        PinLocation.TopLevel,
-                       _settingsModel,
+                       _settingsService,
                        _topLevelCommandManager);
 
                 var contextItem = new PinToContextItem(pinToTopLevelCommand, commandItem);
@@ -168,22 +169,22 @@ internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFac
         List<IContextItem> moreCommands,
         CommandItemViewModel commandItem)
     {
-        if (!_settingsModel.EnableDock)
+        if (!_settingsService.Settings.EnableDock)
         {
             return;
         }
 
-        var inStartBands = _settingsModel.DockSettings.StartBands.Any(band => MatchesBand(band, itemId, providerId));
-        var inCenterBands = _settingsModel.DockSettings.CenterBands.Any(band => MatchesBand(band, itemId, providerId));
-        var inEndBands = _settingsModel.DockSettings.EndBands.Any(band => MatchesBand(band, itemId, providerId));
+        var inStartBands = _settingsService.Settings.DockSettings.StartBands.Any(band => MatchesBand(band, itemId, providerId));
+        var inCenterBands = _settingsService.Settings.DockSettings.CenterBands.Any(band => MatchesBand(band, itemId, providerId));
+        var inEndBands = _settingsService.Settings.DockSettings.EndBands.Any(band => MatchesBand(band, itemId, providerId));
         var alreadyPinned = inStartBands || inCenterBands || inEndBands; /** &&
-                            _settingsModel.DockSettings.PinnedCommands.Contains(this.Id)**/
+                            _settingsService.Settings.DockSettings.PinnedCommands.Contains(this.Id)**/
         var pinToTopLevelCommand = new PinToCommand(
             commandId: itemId,
             providerId: providerId,
             pin: !alreadyPinned,
             PinLocation.Dock,
-            _settingsModel,
+            _settingsService,
             _topLevelCommandManager);
 
         var contextItem = new PinToContextItem(pinToTopLevelCommand, commandItem);
@@ -231,7 +232,7 @@ internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFac
     {
         private readonly string _commandId;
         private readonly string _providerId;
-        private readonly SettingsModel _settings;
+        private readonly ISettingsService _settingsService;
         private readonly TopLevelCommandManager _topLevelCommandManager;
         private readonly bool _pin;
         private readonly PinLocation _pinLocation;
@@ -251,13 +252,13 @@ internal sealed partial class CommandPaletteContextMenuFactory : IContextMenuFac
             string providerId,
             bool pin,
             PinLocation pinLocation,
-            SettingsModel settings,
+            ISettingsService settingsService,
             TopLevelCommandManager topLevelCommandManager)
         {
             _commandId = commandId;
             _providerId = providerId;
             _pinLocation = pinLocation;
-            _settings = settings;
+            _settingsService = settingsService;
             _topLevelCommandManager = topLevelCommandManager;
             _pin = pin;
         }