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/unit/__mocks__/README.md

@@ -0,0 +1,153 @@
+# n8n-nodes-base Mock
+
+This directory contains comprehensive mocks for n8n packages used in unit tests.
+
+## n8n-nodes-base Mock
+
+The `n8n-nodes-base.ts` mock provides a complete testing infrastructure for code that depends on n8n nodes.
+
+### Features
+
+1. **Pre-configured Node Types**
+   - `webhook` - Trigger node with webhook functionality
+   - `httpRequest` - HTTP request node with mock responses
+   - `slack` - Slack integration with all resources and operations
+   - `function` - JavaScript code execution node
+   - `noOp` - Pass-through utility node
+   - `merge` - Data stream merging node
+   - `if` - Conditional branching node
+   - `switch` - Multi-output routing node
+
+2. **Flexible Mock Behavior**
+   - Override node execution logic
+   - Customize node descriptions
+   - Add custom nodes dynamically
+   - Reset all mocks between tests
+
+### Basic Usage
+
+```typescript
+import { vi } from 'vitest';
+
+// Mock the module
+vi.mock('n8n-nodes-base', () => import('../__mocks__/n8n-nodes-base'));
+
+// In your test
+import { getNodeTypes, mockNodeBehavior, resetAllMocks } from '../__mocks__/n8n-nodes-base';
+
+describe('Your test', () => {
+  beforeEach(() => {
+    resetAllMocks();
+  });
+
+  it('should get node description', () => {
+    const registry = getNodeTypes();
+    const slackNode = registry.getByName('slack');
+    
+    expect(slackNode?.description.name).toBe('slack');
+  });
+});
+```
+
+### Advanced Usage
+
+#### Override Node Behavior
+
+```typescript
+mockNodeBehavior('httpRequest', {
+  execute: async function(this: IExecuteFunctions) {
+    return [[{ json: { custom: 'response' } }]];
+  }
+});
+```
+
+#### Add Custom Nodes
+
+```typescript
+import { registerMockNode } from '../__mocks__/n8n-nodes-base';
+
+const customNode = {
+  description: {
+    displayName: 'Custom Node',
+    name: 'customNode',
+    group: ['transform'],
+    version: 1,
+    description: 'A custom test node',
+    defaults: { name: 'Custom' },
+    inputs: ['main'],
+    outputs: ['main'],
+    properties: []
+  },
+  execute: async function() {
+    return [[{ json: { result: 'custom' } }]];
+  }
+};
+
+registerMockNode('customNode', customNode);
+```
+
+#### Mock Execution Context
+
+```typescript
+const mockContext = {
+  getInputData: vi.fn(() => [{ json: { test: 'data' } }]),
+  getNodeParameter: vi.fn((name: string) => {
+    const params = {
+      method: 'POST',
+      url: 'https://api.example.com'
+    };
+    return params[name];
+  }),
+  getCredentials: vi.fn(async () => ({ apiKey: 'test-key' })),
+  helpers: {
+    returnJsonArray: vi.fn(),
+    httpRequest: vi.fn()
+  }
+};
+
+const result = await node.execute.call(mockContext);
+```
+
+### Mock Structure
+
+Each mock node implements the `INodeType` interface with:
+
+- `description`: Complete node metadata including properties, inputs/outputs, credentials
+- `execute`: Mock implementation for regular nodes (returns `INodeExecutionData[][]`)
+- `webhook`: Mock implementation for trigger nodes (returns webhook data)
+
+### Testing Patterns
+
+1. **Unit Testing Node Logic**
+   ```typescript
+   const node = registry.getByName('slack');
+   const result = await node.execute.call(mockContext);
+   expect(result[0][0].json.ok).toBe(true);
+   ```
+
+2. **Testing Node Properties**
+   ```typescript
+   const node = registry.getByName('httpRequest');
+   const methodProp = node.description.properties.find(p => p.name === 'method');
+   expect(methodProp.options).toHaveLength(6);
+   ```
+
+3. **Testing Conditional Nodes**
+   ```typescript
+   const ifNode = registry.getByName('if');
+   const [trueOutput, falseOutput] = await ifNode.execute.call(mockContext);
+   expect(trueOutput).toHaveLength(2);
+   expect(falseOutput).toHaveLength(1);
+   ```
+
+### Utilities
+
+- `resetAllMocks()` - Clear all mock function calls
+- `mockNodeBehavior(name, overrides)` - Override specific node behavior
+- `registerMockNode(name, node)` - Add new mock nodes
+- `getNodeTypes()` - Get the node registry with `getByName` and `getByNameAndVersion`
+
+### See Also
+
+- `tests/unit/examples/using-n8n-nodes-base-mock.test.ts` - Complete usage examples
+- `tests/unit/__mocks__/n8n-nodes-base.test.ts` - Mock test coverage