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

.agent/workflows/bmad/bmad-core-workflows-party-mode.md

@@ -0,0 +1,5 @@
+---
+description: 'Orchestrates group discussions between all installed BMAD agents, enabling natural multi-agent conversations'
+---
+
+IT IS CRITICAL THAT YOU FOLLOW THIS COMMAND: LOAD the FULL @_bmad/core/workflows/party-mode/workflow.md, READ its entire contents and follow its directions exactly!