feat(backend): Express + Socket.IO API with PostgreSQL

- Auth: register/login/me with bcrypt (12 rounds) and JWT bearer tokens
- Workspaces: CRUD, role-based members (owner/admin/member/viewer), invite by email
- Pages: nested hierarchy, TipTap JSON+HTML content, archive, search, comments
- Realtime: Socket.IO rooms per page with JWT handshake, live edits, presence, typing
- DB schema with triggers (owner membership, updated_at) and migrate script
- Helmet, CORS allow-list, rate limiting, /api/health with DB check
- Dockerfile (migrate-on-boot) for compose/production

backend/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "openstack-backend",
+  "version": "0.1.0",
+  "description": "Express + Socket.IO API for openStack",
+  "main": "src/index.js",
+  "scripts": {
+    "start": "node src/index.js",
+    "dev": "node --watch src/index.js",
+    "migrate": "node src/db/migrate.js",
+    "test": "node --test test/*.test.js"
+  },
+  "dependencies": {
+    "bcryptjs": "^2.4.3",
+    "cors": "^2.8.5",
+    "dotenv": "^16.4.5",
+    "express": "^4.19.2",
+    "express-rate-limit": "^7.2.0",
+    "helmet": "^7.1.0",
+    "jsonwebtoken": "^9.0.2",
+    "morgan": "^1.10.0",
+    "pg": "^8.12.0",
+    "socket.io": "^4.7.5"
+  }
+}