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>

types/test-env.d.ts

@@ -0,0 +1,106 @@
+/**
+ * Type definitions for test environment variables
+ */
+
+declare global {
+  namespace NodeJS {
+    interface ProcessEnv {
+      // Core Environment
+      NODE_ENV: 'test' | 'development' | 'production';
+      MCP_MODE?: 'test' | 'http' | 'stdio';
+      TEST_ENVIRONMENT?: string;
+
+      // Database Configuration
+      NODE_DB_PATH: string;
+      REBUILD_ON_START?: string;
+      TEST_SEED_DATABASE?: string;
+      TEST_SEED_TEMPLATES?: string;
+
+      // API Configuration
+      N8N_API_URL: string;
+      N8N_API_KEY: string;
+      N8N_WEBHOOK_BASE_URL?: string;
+      N8N_WEBHOOK_TEST_URL?: string;
+
+      // Server Configuration
+      PORT?: string;
+      HOST?: string;
+      CORS_ORIGIN?: string;
+
+      // Authentication
+      AUTH_TOKEN?: string;
+      MCP_AUTH_TOKEN?: string;
+
+      // Logging
+      LOG_LEVEL?: 'debug' | 'info' | 'warn' | 'error';
+      DEBUG?: string;
+      TEST_LOG_VERBOSE?: string;
+      ERROR_SHOW_STACK?: string;
+      ERROR_SHOW_DETAILS?: string;
+
+      // Test Timeouts
+      TEST_TIMEOUT_UNIT?: string;
+      TEST_TIMEOUT_INTEGRATION?: string;
+      TEST_TIMEOUT_E2E?: string;
+      TEST_TIMEOUT_GLOBAL?: string;
+
+      // Test Execution
+      TEST_RETRY_ATTEMPTS?: string;
+      TEST_RETRY_DELAY?: string;
+      TEST_PARALLEL?: string;
+      TEST_MAX_WORKERS?: string;
+
+      // Feature Flags
+      FEATURE_TEST_COVERAGE?: string;
+      FEATURE_TEST_SCREENSHOTS?: string;
+      FEATURE_TEST_VIDEOS?: string;
+      FEATURE_TEST_TRACE?: string;
+      FEATURE_MOCK_EXTERNAL_APIS?: string;
+      FEATURE_USE_TEST_CONTAINERS?: string;
+
+      // Mock Services
+      MSW_ENABLED?: string;
+      MSW_API_DELAY?: string;
+      REDIS_MOCK_ENABLED?: string;
+      REDIS_MOCK_PORT?: string;
+      ELASTICSEARCH_MOCK_ENABLED?: string;
+      ELASTICSEARCH_MOCK_PORT?: string;
+
+      // Test Paths
+      TEST_FIXTURES_PATH?: string;
+      TEST_DATA_PATH?: string;
+      TEST_SNAPSHOTS_PATH?: string;
+
+      // Performance Thresholds
+      PERF_THRESHOLD_API_RESPONSE?: string;
+      PERF_THRESHOLD_DB_QUERY?: string;
+      PERF_THRESHOLD_NODE_PARSE?: string;
+
+      // Rate Limiting
+      RATE_LIMIT_MAX?: string;
+      RATE_LIMIT_WINDOW?: string;
+
+      // Caching
+      CACHE_TTL?: string;
+      CACHE_ENABLED?: string;
+
+      // Cleanup
+      TEST_CLEANUP_ENABLED?: string;
+      TEST_CLEANUP_ON_FAILURE?: string;
+
+      // Network
+      NETWORK_TIMEOUT?: string;
+      NETWORK_RETRY_COUNT?: string;
+
+      // Memory
+      TEST_MEMORY_LIMIT?: string;
+
+      // Coverage
+      COVERAGE_DIR?: string;
+      COVERAGE_REPORTER?: string;
+    }
+  }
+}
+
+// Export empty object to make this a module
+export {};