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/2-plan-workflows/prd/templates/prd-template.md

@@ -0,0 +1,10 @@
+---
+stepsCompleted: []
+inputDocuments: []
+workflowType: 'prd'
+---
+
+# Product Requirements Document - {{project_name}}
+
+**Author:** {{user_name}}
+**Date:** {{date}}