Add full test suite with unit, integration, and E2E smoke tests.

Introduce test.bat orchestrating Go/Vitest/Playwright phases, expand coverage across server, agent, and dashboard, and document in tests/README.md.

server/web/package.json

@@ -7,7 +7,9 @@
     "dev": "vite",
     "build": "tsc && vite build",
     "preview": "vite preview",
-    "test": "vitest run"
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:e2e": "playwright test"
   },
   "dependencies": {
     "@react-three/drei": "^9.114.0",
@@ -22,9 +24,11 @@
     "three": "^0.170.0"
   },
   "devDependencies": {
+    "@playwright/test": "^1.49.0",
     "@types/react": "^18.2.37",
     "@types/react-dom": "^18.2.15",
     "@vitejs/plugin-react": "^4.2.0",
+    "happy-dom": "^15.11.7",
     "typescript": "^5.2.2",
     "vite": "^5.0.0",
     "vitest": "^2.1.9"