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>

scripts/vitest-benchmark-json-reporter.js

@@ -0,0 +1,73 @@
+import { writeFileSync } from 'fs';
+import { resolve } from 'path';
+
+export default class BenchmarkJsonReporter {
+  constructor() {
+    this.results = [];
+  }
+
+  onTaskUpdate(tasks) {
+    // Called when tasks are updated
+  }
+
+  onFinished(files) {
+    const results = {
+      timestamp: new Date().toISOString(),
+      files: []
+    };
+
+    for (const file of files || []) {
+      if (!file) continue;
+      
+      const fileResult = {
+        filepath: file.filepath || file.name,
+        groups: []
+      };
+
+      // Process benchmarks
+      if (file.tasks) {
+        for (const task of file.tasks) {
+          if (task.type === 'suite' && task.tasks) {
+            const group = {
+              name: task.name,
+              benchmarks: []
+            };
+
+            for (const benchmark of task.tasks) {
+              if (benchmark.result?.benchmark) {
+                group.benchmarks.push({
+                  name: benchmark.name,
+                  result: {
+                    mean: benchmark.result.benchmark.mean,
+                    min: benchmark.result.benchmark.min,
+                    max: benchmark.result.benchmark.max,
+                    hz: benchmark.result.benchmark.hz,
+                    p75: benchmark.result.benchmark.p75,
+                    p99: benchmark.result.benchmark.p99,
+                    p995: benchmark.result.benchmark.p995,
+                    p999: benchmark.result.benchmark.p999,
+                    rme: benchmark.result.benchmark.rme,
+                    samples: benchmark.result.benchmark.samples
+                  }
+                });
+              }
+            }
+
+            if (group.benchmarks.length > 0) {
+              fileResult.groups.push(group);
+            }
+          }
+        }
+      }
+
+      if (fileResult.groups.length > 0) {
+        results.files.push(fileResult);
+      }
+    }
+
+    // Write results
+    const outputPath = resolve(process.cwd(), 'benchmark-results.json');
+    writeFileSync(outputPath, JSON.stringify(results, null, 2));
+    console.log(`Benchmark results written to ${outputPath}`);
+  }
+}