refactor(tray): extract Settings page into a WinUI-free view model over a settings store

[bkudiess]

Moves the Settings page's settings read/persist logic out of the code-behind into a WinUI-free view model backed by a new settings facade, as a behavior-and-visual-identical refactor. First page to adopt the merged DI + navigation activation seam and the first visible reduction of a page god-file.

What changed

• Add ISettingsStore (SettingsStore): immutable snapshot read, batched Update, a single non-echoing Changed (self-originated saves suppressed; external saves marshaled to the UI thread), and BeginSelfWrite() so App-owned direct writes (auto-start OS registration, speaker mute from Settings) share the same echo suppression.
• Add SettingsPageViewModel (WinUI-free): two-way-bindable settings state that persists through the store, preserving the save/notify contract and the read-aloud / tool-call side effects, reloading on external change without re-persisting, and normalizing combo values so a legacy tag never renders blank.
• Add SettingsAppInfoProjection (WinUI-free) for the About section strings.
• Bind SettingsPage.xaml to the view model; shrink the code-behind (about -258 lines) to the remaining view concerns (gateway removal dialog, uptime timer, saved indicator, app-info, gateway-section refresh on external change).
• Populate the page to view-model map so the navigation hook resolves and binds the view model; add ApplyAutoStart / SetChatSpeakerMuted / SetChatToolCallsVisible to the app-commands adapter, with mute suppression scoped to the Settings-originated call so a mute toggled elsewhere still refreshes an open Settings page.
• Record settings-store and settings-page-vm in the architecture ledger with behavioral guard tests.

Validation

• ./build.ps1
• dotnet test tests/OpenClaw.Shared.Tests (3170 passed)
• dotnet test tests/OpenClaw.Tray.Tests (1954 passed)

New tests cover the store (self-write suppression, external-change echo, depth reset), the view model (field mapping, save/notify ordering, no-echo, combo normalization, auto-start success/failure), and the app-info projection; ledger consistency passes.

Real behavior proof

Isolated build: navigated to Settings via the node app.navigate command; toggles and combos persist to settings.json and flash the Saved indicator; a legacy value renders the correct item instead of a blank combo; Start-with-Windows persists through the ordered auto-start path and shows Saved only after it persists; the About section renders the runtime/version/channel/build-date projection; values survive an app restart with no spurious save on open. Renders identically to the pre-change page.

[clawsweeper]

ClawSweeper status: review started.

I am starting a fresh review of this pull request: refactor(tray): extract Settings page into a WinUI-free view model over a settings store This is item 1/1 in the current shard. Shard 0/1.

This placeholder means the worker is alive and reading the current context. I will edit this same comment with the actual review when the claws are done clicking.

Crustacean status: shell secured, claws on keyboard, evidence pebbles being sorted.