feat: add comprehensive integration tests for auto-mode-service

- Created git-test-repo helper for managing test git repositories
- Added 13 integration tests covering:
  - Worktree operations (create, error handling, non-worktree mode)
  - Feature execution (status updates, model selection, duplicate prevention)
  - Auto loop (start/stop, pending features, max concurrency, events)
  - Error handling (provider errors, continue after failures)
- Integration tests use real git operations with temporary repos
- All 416 tests passing with 72.65% overall coverage
- Service coverage improved: agent-service 58%, auto-mode-service 44%, feature-loader 66%

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/server/package.json

@@ -9,7 +9,13 @@
     "dev": "tsx watch src/index.ts",
     "build": "tsc",
     "start": "node dist/index.js",
-    "lint": "eslint src/"
+    "lint": "eslint src/",
+    "test": "vitest",
+    "test:ui": "vitest --ui",
+    "test:run": "vitest run",
+    "test:cov": "vitest run --coverage",
+    "test:watch": "vitest watch",
+    "test:unit": "vitest run tests/unit"
   },
   "dependencies": {
     "@anthropic-ai/claude-agent-sdk": "^0.1.61",
@@ -23,7 +29,10 @@
     "@types/express": "^5.0.1",
     "@types/node": "^20",
     "@types/ws": "^8.18.1",
+    "@vitest/coverage-v8": "^4.0.15",
+    "@vitest/ui": "^4.0.15",
     "tsx": "^4.19.4",
-    "typescript": "^5"
+    "typescript": "^5",
+    "vitest": "^4.0.15"
   }
 }