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/core/tasks/shard-doc.xml

@@ -1,4 +1,4 @@
-<tool id="_bmad/core/tasks/shard-doc" name="Shard Document"
+<task id="_bmad/core/tasks/shard-doc" name="Shard Document"
   description="Splits large markdown documents into smaller, organized files based on level 2 (default) sections" webskip="true"
   standalone="true">
   <objective>Split large markdown documents into smaller, organized files based on level 2 sections using @kayvan/markdown-tree-parser tool</objective>
@@ -106,4 +106,4 @@
   <halt-conditions critical="true">
     <i>HALT if npx command fails or produces no output files</i>
   </halt-conditions>
-</tool>
+</task>