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/sprint-status/workflow.yaml

@@ -19,14 +19,14 @@ instructions: "{installed_path}/instructions.md"
 
 # Inputs
 variables:
-  sprint_status_file: "{implementation_artifacts}/sprint-status.yaml || {output_folder}/sprint-status.yaml"
+  sprint_status_file: "{implementation_artifacts}/sprint-status.yaml"
   tracking_system: "file-system"
 
 # Smart input file references
 input_file_patterns:
   sprint_status:
     description: "Sprint status file generated by sprint-planning"
-    whole: "{implementation_artifacts}/sprint-status.yaml || {output_folder}/sprint-status.yaml"
+    whole: "{implementation_artifacts}/sprint-status.yaml"
     load_strategy: "FULL_LOAD"
 
 # Standalone so IDE commands get generated