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

keep-notes/tests/migration/README.md

@@ -0,0 +1,156 @@
+# Migration Tests
+
+This directory contains comprehensive test suites for validating Prisma schema and data migrations for the Keep notes application.
+
+## Test Files
+
+- **setup.ts** - Test utilities for database setup, teardown, and test data generation
+- **schema-migration.test.ts** - Validates schema migrations (tables, columns, indexes, relationships)
+- **data-migration.test.ts** - Validates data migration (transformation, integrity, edge cases)
+- **rollback.test.ts** - Validates rollback capability and data recovery
+- **performance.test.ts** - Validates migration performance with various dataset sizes
+- **integrity.test.ts** - Validates data integrity (no loss/corruption, foreign keys, indexes)
+
+## Running Tests
+
+### Run all migration tests
+```bash
+npm run test:migration
+```
+
+### Run migration tests in watch mode
+```bash
+npm run test:migration:watch
+```
+
+### Run specific test file
+```bash
+npm run test:unit tests/migration/schema-migration.test.ts
+```
+
+### Run tests with coverage
+```bash
+npm run test:unit:coverage
+```
+
+## Test Coverage Goals
+
+- **Minimum threshold:** 80% coverage for migration-related code
+- **Coverage areas:** Migration scripts, test utilities, schema transformations
+- **Exclude from coverage:** Test files themselves (`*.test.ts`)
+
+## Test Structure
+
+### Schema Migration Tests
+- Core table existence (User, Note, Notebook, Label, etc.)
+- AI feature tables (AiFeedback, MemoryEchoInsight, UserAISettings)
+- Note table AI fields (autoGenerated, aiProvider, aiConfidence, etc.)
+- Index creation on critical fields
+- Foreign key relationships
+- Unique constraints
+- Default values
+
+### Data Migration Tests
+- Empty database migration
+- Basic note migration
+- AI fields data migration
+- AiFeedback data migration
+- MemoryEchoInsight data migration
+- UserAISettings data migration
+- Data integrity verification
+- Edge cases (empty strings, long content, special characters)
+- Performance benchmarks
+
+### Rollback Tests
+- Schema state verification
+- Column/table rollback simulation
+- Data recovery after rollback
+- Orphaned record handling
+- Rollback safety checks
+- Rollback error handling
+
+### Performance Tests
+- Empty migration (< 1 second)
+- Small dataset (10 notes) (< 1 second)
+- Medium dataset (100 notes) (< 5 seconds)
+- Target dataset (1,000 notes) (< 30 seconds)
+- Stress test (10,000 notes) (< 30 seconds)
+- AI features performance
+- Database size tracking
+- Concurrent operations
+
+### Integrity Tests
+- No data loss
+- No data corruption
+- Foreign key relationship maintenance
+- Index integrity
+- AI fields preservation
+- Batch operations integrity
+- Data type integrity
+
+## Test Utilities
+
+The `setup.ts` file provides reusable utilities:
+
+- `setupTestEnvironment()` - Initialize test environment
+- `createTestPrismaClient()` - Create isolated Prisma client
+- `initializeTestDatabase()` - Apply all migrations
+- `cleanupTestDatabase()` - Clean up test database
+- `createSampleNotes()` - Generate sample test notes
+- `createSampleAINotes()` - Generate AI-enabled test notes
+- `measureExecutionTime()` - Performance measurement helper
+- `verifyDataIntegrity()` - Data integrity checks
+- `verifyTableExists()` - Table existence verification
+- `verifyColumnExists()` - Column existence verification
+- `verifyIndexExists()` - Index existence verification
+- `getTableSchema()` - Get table schema information
+- `getDatabaseSize()` - Get database file size
+
+## Acceptance Criteria Coverage
+
+✅ **AC 1:** Unit tests exist for all migration scripts
+✅ **AC 2:** Integration tests verify database state before/after migrations
+✅ **AC 3:** Test suite validates rollback capability
+✅ **AC 4:** Performance tests ensure migrations complete within acceptable limits
+✅ **AC 5:** Tests verify data integrity (no loss/corruption)
+✅ **AC 6:** Test coverage meets minimum threshold (80%)
+
+## CI/CD Integration
+
+These tests are configured to run in CI/CD pipelines:
+
+```yaml
+# Example CI configuration
+- name: Run migration tests
+  run: npm run test:migration
+
+- name: Check coverage
+  run: npm run test:unit:coverage
+```
+
+## Isolation
+
+Each test suite runs in an isolated test database:
+- **Location:** `prisma/test-databases/migration-test.db`
+- **Lifecycle:** Created before test suite, deleted after
+- **Conflict:** No conflict with development database
+
+## Troubleshooting
+
+### Tests fail with database locked error
+Ensure no other process is using the test database. The test utilities automatically clean up the test database.
+
+### Tests timeout
+Increase timeout values in `vitest.config.ts` if necessary.
+
+### Coverage below threshold
+Review coverage report in `coverage/index.html` to identify untested code.
+
+## Contributing
+
+When adding new migrations:
+
+1. Add corresponding test cases in appropriate test files
+2. Update this README with new test coverage
+3. Ensure coverage threshold (80%) is maintained
+4. Run all migration tests before committing