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/benchmarks/README.md

@@ -0,0 +1,121 @@
+# Performance Benchmarks
+
+This directory contains performance benchmarks for critical operations in the n8n-mcp project.
+
+## Running Benchmarks
+
+### Local Development
+
+```bash
+# Run all benchmarks
+npm run benchmark
+
+# Watch mode for development
+npm run benchmark:watch
+
+# Interactive UI
+npm run benchmark:ui
+
+# Run specific benchmark file
+npx vitest bench tests/benchmarks/node-loading.bench.ts
+```
+
+### CI/CD
+
+Benchmarks run automatically on:
+- Every push to `main` branch
+- Every pull request
+- Manual workflow dispatch
+
+## Benchmark Suites
+
+### 1. Node Loading Performance (`node-loading.bench.ts`)
+- Package loading (n8n-nodes-base, @n8n/n8n-nodes-langchain)
+- Individual node file loading
+- Package.json parsing
+
+### 2. Database Query Performance (`database-queries.bench.ts`)
+- Node retrieval by type
+- Category filtering
+- Search operations (OR, AND, FUZZY modes)
+- Node counting and statistics
+- Insert/update operations
+
+### 3. Search Operations (`search-operations.bench.ts`)
+- Single and multi-word searches
+- Exact phrase matching
+- Fuzzy search performance
+- Property search within nodes
+- Complex filtering operations
+
+### 4. Validation Performance (`validation-performance.bench.ts`)
+- Node configuration validation (minimal, strict, ai-friendly)
+- Expression validation
+- Workflow validation
+- Property dependency resolution
+
+### 5. MCP Tool Execution (`mcp-tools.bench.ts`)
+- Tool execution overhead
+- Response formatting
+- Complex query handling
+
+## Performance Targets
+
+| Operation | Target | Alert Threshold |
+|-----------|--------|-----------------|
+| Node loading | <100ms per package | >150ms |
+| Database query | <5ms per query | >10ms |
+| Search (simple) | <10ms | >20ms |
+| Search (complex) | <50ms | >100ms |
+| Validation (simple) | <1ms | >2ms |
+| Validation (complex) | <10ms | >20ms |
+| MCP tool execution | <50ms | >100ms |
+
+## Benchmark Results
+
+- Results are tracked over time using GitHub Actions
+- Historical data available at: https://czlonkowski.github.io/n8n-mcp/benchmarks/
+- Performance regressions >10% trigger automatic alerts
+- PR comments show benchmark comparisons
+
+## Writing New Benchmarks
+
+```typescript
+import { bench, describe } from 'vitest';
+
+describe('My Performance Suite', () => {
+  bench('operation name', async () => {
+    // Code to benchmark
+  }, {
+    iterations: 100,        // Number of times to run
+    warmupIterations: 10,   // Warmup runs (not measured)
+    warmupTime: 500,        // Warmup duration in ms
+    time: 3000             // Total benchmark duration in ms
+  });
+});
+```
+
+## Best Practices
+
+1. **Isolate Operations**: Benchmark specific operations, not entire workflows
+2. **Use Realistic Data**: Load actual n8n nodes for realistic measurements
+3. **Warmup**: Always include warmup iterations to avoid JIT compilation effects
+4. **Memory**: Use in-memory databases for consistent results
+5. **Iterations**: Balance between accuracy and execution time
+
+## Troubleshooting
+
+### Inconsistent Results
+- Increase `warmupIterations` and `warmupTime`
+- Run benchmarks in isolation
+- Check for background processes
+
+### Memory Issues
+- Reduce `iterations` for memory-intensive operations
+- Add cleanup in `afterEach` hooks
+- Monitor memory usage during benchmarks
+
+### CI Failures
+- Check benchmark timeout settings
+- Verify GitHub Actions runner resources
+- Review alert thresholds for false positives