Clean working version: deployed TypeScript backend + JSX frontend

- Replace old JS backend with working TypeScript backend from deployed containers
- Backend: Fastify + better-sqlite3 + Yjs CRDT, 17 TS source files, 13 test files
- Frontend: React JSX with fabric.js CAD canvas, vite build, nginx serving
- Fix nginx proxy port 5000→3001 to match backend
- Fix docker-compose port mapping 5000→3001
- Fix vite dev proxy port 5000→3001
- Add backend healthcheck to docker-compose
- Update index.html title to 'Web CAD', lang to 'de'
- Add .a0/ to .gitignore
- Remove old JS backend files (models, routes, config, middleware, seed)
- Remove tracked build artifacts (backend/public/)

backend/package.json

@@ -1,25 +1,31 @@
 {
-  "name": "backend",
-  "version": "1.0.0",
-  "description": "",
-  "main": "index.js",
+  "name": "web-cad-backend",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "dev": "tsx watch src/index.ts",
+    "build": "tsc",
+    "postbuild": "cp src/database/schema.sql dist/database/schema.sql",
+    "start": "node dist/index.js",
+    "test": "vitest run"
   },
-  "keywords": [],
-  "author": "",
-  "license": "ISC",
   "dependencies": {
-    "bcryptjs": "^3.0.3",
-    "cors": "^2.8.6",
-    "dxf-parser": "^1.1.2",
-    "express": "^5.2.1",
-    "jsonwebtoken": "^9.0.3",
-    "multer": "^2.1.1",
-    "passport": "^0.7.0",
-    "passport-jwt": "^4.0.1",
-    "passport-local": "^1.0.0",
-    "pg": "^8.21.0",
-    "sequelize": "^6.37.8"
+    "@fastify/cors": "^9.0.0",
+    "@fastify/static": "^7.0.0",
+    "@fastify/websocket": "^10.0.0",
+    "bcrypt": "^6.0.0",
+    "better-sqlite3": "^11.0.0",
+    "fastify": "^4.28.0",
+    "y-leveldb": "^0.2.0",
+    "yjs": "^13.6.0"
+  },
+  "devDependencies": {
+    "@types/bcrypt": "^6.0.0",
+    "@types/better-sqlite3": "^7.6.0",
+    "@types/node": "^20.14.0",
+    "tsx": "^4.16.0",
+    "typescript": "^5.5.0",
+    "vitest": "^2.0.0"
   }
-}
+}