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/factories/node-factory.ts

@@ -0,0 +1,21 @@
+import { Factory } from 'fishery';
+import { faker } from '@faker-js/faker';
+import { ParsedNode } from '../../src/parsers/node-parser';
+
+export const NodeFactory = Factory.define<ParsedNode>(() => ({
+  nodeType: faker.helpers.arrayElement(['nodes-base.', 'nodes-langchain.']) + faker.word.noun(),
+  displayName: faker.helpers.arrayElement(['HTTP', 'Slack', 'Google', 'AWS']) + ' ' + faker.word.noun(),
+  description: faker.lorem.sentence(),
+  packageName: faker.helpers.arrayElement(['n8n-nodes-base', '@n8n/n8n-nodes-langchain']),
+  category: faker.helpers.arrayElement(['transform', 'trigger', 'output', 'input']),
+  style: faker.helpers.arrayElement(['declarative', 'programmatic']),
+  isAITool: faker.datatype.boolean(),
+  isTrigger: faker.datatype.boolean(),
+  isWebhook: faker.datatype.boolean(),
+  isVersioned: faker.datatype.boolean(),
+  version: faker.helpers.arrayElement(['1.0', '2.0', '3.0', '4.2']),
+  documentation: faker.datatype.boolean() ? faker.lorem.paragraphs(3) : undefined,
+  properties: [],
+  operations: [],
+  credentials: []
+}));