Add in​-app dashboard log viewer with shared runtime log store

[JoshuaMorris]

Summary

Adds a native in-app log viewer to the main dashboard so users can inspect recent server/app activity without relying on Xcode console output.

What Changed

• Added AppLogStore (ObservableObject) for a capped in-memory log buffer.
• Added AppLog helper to log to both OSLog and in-app store.
• Added a dedicated Logs section in the dashboard with:
  • timestamp + severity + source + message
  • scrollable list
  • auto-scroll toggle
  • Copy button
  • Clear button
• Wired key runtime events into the shared log store:
  • app startup
  • server start/stop/restart and port binding/fallback
  • auth failures and request handling
  • relay lifecycle/errors
  • inference lifecycle/errors
  • guardrail/refusal and fallback events

Behavior / Compatibility

• Existing behavior preserved; changes are additive.
• Existing system logging remains intact.
• No third-party dependencies.

Validation

• Builds successfully in Xcode.
• Logs appear live in the dashboard during server operations and requests.

Limitations

• Logs are in-memory only (not persisted across app restarts).