feat: initial commit — local services (backend + manager dashboard + waiter PWA)

Includes all work to date:
- local_backend: FastAPI backend with products, orders, tables, shifts, cloud sync
- manager_dashboard: React manager UI with product/category management, reports, settings
- waiter_pwa: React PWA for waiter devices
- Category reparent endpoint and UI
- Waiter domain: local_ip sent on heartbeat, waiter_domain persisted from cloud response
- QR code modal in AppInfoTab for waiter domain
- Product form: number input spinners removed, category pre-selected on new product
- Category row: count badge moved to far right

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

waiter_pwa/nginx.conf

@@ -0,0 +1,22 @@
+server {
+    listen 80;
+
+    root /usr/share/nginx/html;
+    index index.html;
+
+    location /api/ {
+        proxy_pass http://backend:8000;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_read_timeout 3600;
+    }
+
+    location /static/ {
+        proxy_pass http://backend:8000/static/;
+        proxy_set_header Host $host;
+    }
+
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+}