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/bmm/workflows/4-implementation/create-story/instructions.xml

@@ -336,9 +336,10 @@
       1. Review the comprehensive story in {{story_file}}
       2. Run dev agents `dev-story` for optimized implementation
       3. Run `code-review` when complete (auto-marks done)
+      4. Optional: Run TEA `*automate` after `dev-story` to generate guardrail tests
 
       **The developer now has everything needed for flawless implementation!**
     </output>
   </step>
 
-</workflow>
+</workflow>