Replace frontend with deployed TS version from a08dd73

- Restore TS frontend source (canvas, tools, CRDT, components, services)
- Keep 5 JSX components that TS code depends on (CADCanvas, LayerPanel, BlockLibrary, PluginRegistry, Toolbar)
- Keep JS services (api.js, blockService.js) that components depend on
- Fix vite/plugin-react version mismatch (downgrade to v4 for vite 6)
- Add axios dependency
- Skip tsc in build script (vite/esbuild handles transpilation)
- Fix index.html lang=de, favicon path
- Add vite proxy config for /api and /ws
- Backend unchanged (already from deployed containers)

frontend/nginx.conf

@@ -1,24 +1,25 @@
 server {
-  listen 80;
-  root /usr/share/nginx/html;
-  index index.html;
+    listen 80;
+    server_name localhost;
 
-  resolver 127.0.0.11 valid=30s;
+    root /usr/share/nginx/html;
+    index index.html;
 
-  location / { try_files $uri $uri/ /index.html; }
+    # Serve static frontend
+    location / {
+        try_files $uri /index.html;
+    }
 
-  location /api/ {
-    set $backend http://backend:3001;
-    proxy_pass $backend;
-    proxy_set_header Host $host;
-    proxy_set_header X-Real-IP $remote_addr;
-  }
-
-  location /ws {
-    set $backend http://backend:3001;
-    proxy_pass $backend;
-    proxy_http_version 1.1;
-    proxy_set_header Upgrade $http_upgrade;
-    proxy_set_header Connection "upgrade";
-  }
+    # Proxy API requests to backend
+    location /api/ {
+        proxy_pass http://backend:5000;
+        proxy_http_version 1.1;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection 'upgrade';
+        proxy_set_header Host $host;
+        proxy_cache_bypass $http_upgrade;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
 }