fix: unify theme system - fix theme switching persistence

- Unified localStorage key to 'theme-preference' across all components
- Fixed header.tsx using wrong localStorage key ('theme' instead of 'theme-preference')
- Added localStorage hybrid persistence for instant theme changes
- Removed router.refresh() which was causing stale data revert
- Replaced Blue theme with Sepia
- Consolidated auth() calls to prevent race conditions
- Updated UserSettingsData types to include all themes

_bmad/_config/ides/claude-code.yaml

@@ -1,6 +1,6 @@
 ide: claude-code
 configured_date: 2026-01-09T12:45:17.212Z
-last_updated: 2026-01-09T12:45:17.212Z
+last_updated: 2026-01-18T13:25:57.201Z
 configuration:
   subagentChoices: null
   installLocation: null