feat: add comprehensive performance benchmark tracking system

- Create benchmark test suites for critical operations:
  - Node loading performance
  - Database query performance
  - Search operations performance
  - Validation performance
  - MCP tool execution performance

- Add GitHub Actions workflow for benchmark tracking:
  - Runs on push to main and PRs
  - Uses github-action-benchmark for historical tracking
  - Comments on PRs with performance results
  - Alerts on >10% performance regressions
  - Stores results in GitHub Pages

- Create benchmark infrastructure:
  - Custom Vitest benchmark configuration
  - JSON reporter for CI results
  - Result formatter for github-action-benchmark
  - Performance threshold documentation

- Add supporting utilities:
  - SQLiteStorageService for benchmark database setup
  - MCPEngine wrapper for testing MCP tools
  - Test factories for generating benchmark data
  - Enhanced NodeRepository with benchmark methods

- Document benchmark system:
  - Comprehensive benchmark guide in docs/BENCHMARKS.md
  - Performance thresholds in .github/BENCHMARK_THRESHOLDS.md
  - README for benchmarks directory
  - Integration with existing test suite

The benchmark system will help monitor performance over time and catch regressions before they reach production.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/utils/DATABASE_UTILITIES_SUMMARY.md

@@ -0,0 +1,128 @@
+# Database Testing Utilities Summary
+
+## Overview
+We've created comprehensive database testing utilities for the n8n-mcp project that provide a complete toolkit for database-related testing scenarios.
+
+## Created Files
+
+### 1. `/tests/utils/database-utils.ts`
+The main utilities file containing:
+- **createTestDatabase()** - Creates test databases (in-memory or file-based)
+- **seedTestNodes()** - Seeds test node data
+- **seedTestTemplates()** - Seeds test template data
+- **createTestNode()** - Factory for creating test nodes
+- **createTestTemplate()** - Factory for creating test templates
+- **resetDatabase()** - Clears and reinitializes database
+- **createDatabaseSnapshot()** - Creates database state snapshots
+- **restoreDatabaseSnapshot()** - Restores from snapshots
+- **loadFixtures()** - Loads data from JSON fixtures
+- **dbHelpers** - Collection of common database operations
+- **createMockDatabaseAdapter()** - Creates mock adapter for unit tests
+- **withTransaction()** - Transaction testing helper
+- **measureDatabaseOperation()** - Performance measurement helper
+
+### 2. `/tests/unit/utils/database-utils.test.ts`
+Comprehensive unit tests covering all utility functions with 22 test cases.
+
+### 3. `/tests/fixtures/database/test-nodes.json`
+Example fixture file showing the correct format for nodes and templates.
+
+### 4. `/tests/examples/using-database-utils.test.ts`
+Practical examples showing how to use the utilities in real test scenarios.
+
+### 5. `/tests/integration/database-integration.test.ts`
+Integration test examples demonstrating complex database operations.
+
+### 6. `/tests/utils/README.md`
+Documentation explaining how to use the database utilities.
+
+## Key Features
+
+### 1. Flexible Database Creation
+```typescript
+// In-memory for unit tests (fast, isolated)
+const testDb = await createTestDatabase();
+
+// File-based for integration tests
+const testDb = await createTestDatabase({
+  inMemory: false,
+  dbPath: './test.db'
+});
+```
+
+### 2. Easy Data Seeding
+```typescript
+// Seed with defaults
+await seedTestNodes(testDb.nodeRepository);
+
+// Seed with custom data
+await seedTestNodes(testDb.nodeRepository, [
+  { nodeType: 'custom.node', displayName: 'Custom' }
+]);
+```
+
+### 3. State Management
+```typescript
+// Create snapshot
+const snapshot = await createDatabaseSnapshot(testDb.adapter);
+
+// Do risky operations...
+
+// Restore if needed
+await restoreDatabaseSnapshot(testDb.adapter, snapshot);
+```
+
+### 4. Fixture Support
+```typescript
+// Load complex scenarios from JSON
+await loadFixtures(testDb.adapter, './fixtures/scenario.json');
+```
+
+### 5. Helper Functions
+```typescript
+// Common operations
+dbHelpers.countRows(adapter, 'nodes');
+dbHelpers.nodeExists(adapter, 'node-type');
+dbHelpers.getAllNodeTypes(adapter);
+dbHelpers.clearTable(adapter, 'templates');
+```
+
+## TypeScript Support
+All utilities are fully typed with proper interfaces:
+- `TestDatabase`
+- `TestDatabaseOptions`
+- `DatabaseSnapshot`
+
+## Performance Considerations
+- In-memory databases for unit tests (milliseconds)
+- File-based databases for integration tests
+- Transaction support for atomic operations
+- Performance measurement utilities included
+
+## Best Practices
+1. Always cleanup databases after tests
+2. Use in-memory for unit tests
+3. Use snapshots for complex state management
+4. Keep fixtures versioned with your tests
+5. Test both empty and populated database states
+
+## Integration with Existing Code
+The utilities work seamlessly with:
+- `DatabaseAdapter` from the main codebase
+- `NodeRepository` for node operations
+- `TemplateRepository` for template operations
+- All existing database schemas
+
+## Testing Coverage
+- ✅ All utilities have comprehensive unit tests
+- ✅ Integration test examples provided
+- ✅ Performance testing included
+- ✅ Transaction testing supported
+- ✅ Mock adapter for isolated unit tests
+
+## Usage in CI/CD
+The utilities support:
+- Parallel test execution (isolated databases)
+- Consistent test data across runs
+- Fast execution with in-memory databases
+- No external dependencies required