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/bmad-quick-flow/quick-spec/tech-spec-template.md

@@ -0,0 +1,74 @@
+---
+title: '{title}'
+slug: '{slug}'
+created: '{date}'
+status: 'in-progress'
+stepsCompleted: []
+tech_stack: []
+files_to_modify: []
+code_patterns: []
+test_patterns: []
+---
+
+# Tech-Spec: {title}
+
+**Created:** {date}
+
+## Overview
+
+### Problem Statement
+
+{problem_statement}
+
+### Solution
+
+{solution}
+
+### Scope
+
+**In Scope:**
+{in_scope}
+
+**Out of Scope:**
+{out_of_scope}
+
+## Context for Development
+
+### Codebase Patterns
+
+{codebase_patterns}
+
+### Files to Reference
+
+| File | Purpose |
+| ---- | ------- |
+
+{files_table}
+
+### Technical Decisions
+
+{technical_decisions}
+
+## Implementation Plan
+
+### Tasks
+
+{tasks}
+
+### Acceptance Criteria
+
+{acceptance_criteria}
+
+## Additional Context
+
+### Dependencies
+
+{dependencies}
+
+### Testing Strategy
+
+{testing_strategy}
+
+### Notes
+
+{notes}