v0.1.12

feat: add Settings page for post-setup configuration

Adds a full Settings view accessible after initial setup with:
- Agent service controls (start/stop/restart with live status)
- Autostart toggle (enable/disable OS startup registration)
- Connection config editing (control plane URL, auth token)
- Workspace folder picker
- Save/discard with dirty-state tracking
- Re-run Setup Wizard button

On return visits (config exists), the app now opens directly to Settings
instead of the setup wizard. The wizard remains available via the sidebar
or the 'Re-run Setup Wizard' button.

Also adds a 'Settings' item to the system tray right-click menu that
shows the window and navigates to the Settings view.