test: migrate from Jest to Vitest (Phase 1 complete)

- Remove Jest and all related packages
- Install Vitest with coverage support
- Create vitest.config.ts with path aliases
- Set up global test configuration
- Migrate all 6 test files to Vitest syntax
- Update TypeScript configuration for better Vitest support
- Create separate tsconfig.build.json for clean builds
- Fix all import/module issues in tests
- All 68 tests passing successfully
- Current coverage baseline: 2.45%

Phase 1 of testing suite improvement complete.

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

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

package.json

@@ -7,7 +7,7 @@
     "n8n-mcp": "./dist/mcp/index.js"
   },
   "scripts": {
-    "build": "tsc",
+    "build": "tsc -p tsconfig.build.json",
     "rebuild": "node dist/scripts/rebuild.js",
     "rebuild:optimized": "node dist/scripts/rebuild-optimized.js",
     "validate": "node dist/scripts/validate.js",
@@ -19,7 +19,14 @@
     "dev": "npm run build && npm run rebuild && npm run validate",
     "dev:http": "MCP_MODE=http nodemon --watch src --ext ts --exec 'npm run build && npm run start:http'",
     "test:single-session": "./scripts/test-single-session.sh",
-    "test": "jest",
+    "test": "vitest",
+    "test:ui": "vitest --ui",
+    "test:run": "vitest run",
+    "test:coverage": "vitest run --coverage",
+    "test:watch": "vitest watch",
+    "test:unit": "vitest run tests/unit",
+    "test:integration": "vitest run tests/integration",
+    "test:e2e": "vitest run tests/e2e",
     "lint": "tsc --noEmit",
     "typecheck": "tsc --noEmit",
     "update:n8n": "node scripts/update-n8n-deps.js",
@@ -83,21 +90,24 @@
     "package.runtime.json"
   ],
   "devDependencies": {
+    "@faker-js/faker": "^9.9.0",
+    "@testing-library/jest-dom": "^6.6.4",
     "@types/express": "^5.0.3",
-    "@types/jest": "^29.5.14",
     "@types/node": "^22.15.30",
     "@types/ws": "^8.18.1",
-    "jest": "^29.7.0",
+    "@vitest/coverage-v8": "^3.2.4",
+    "@vitest/ui": "^3.2.4",
+    "fishery": "^2.3.1",
+    "msw": "^2.10.4",
     "nodemon": "^3.1.10",
-    "ts-jest": "^29.3.4",
     "ts-node": "^10.9.2",
-    "typescript": "^5.8.3"
+    "typescript": "^5.8.3",
+    "vitest": "^3.2.4"
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.13.2",
     "@n8n/n8n-nodes-langchain": "^1.102.1",
     "axios": "^1.10.0",
-    "better-sqlite3": "^11.10.0",
     "dotenv": "^16.5.0",
     "express": "^5.1.0",
     "n8n": "^1.103.2",