feat: deposit module — QR flow, PayDepositPage, BookingDetailPanel widget

- Backend: GET /api/pay/:slug (public) — returns active hold confirmation URL
- PayDepositPage: public page /:slug/pay for guests (no login required)
- DepositSettingsPage: QR code section with print button
- BookingDetailPanel: DepositWidget in payment tab
  - Наличными / ЮКасса (QR) buttons
  - hold_created: copy link + refresh
  - hold_confirmed: release form (вернуть / списать)
  - Final status badges

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

package-lock.json

@@ -11,6 +11,7 @@
         "clsx": "^2.1.1",
         "date-fns": "^3.6.0",
         "lucide-react": "^0.446.0",
+        "qrcode.react": "^4.2.0",
         "react": "^18.3.1",
         "react-dom": "^18.3.1",
         "react-router-dom": "^6.26.0",
@@ -2264,6 +2265,15 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/qrcode.react": {
+      "version": "4.2.0",
+      "resolved": "https://registry.npmjs.org/qrcode.react/-/qrcode.react-4.2.0.tgz",
+      "integrity": "sha512-QpgqWi8rD9DsS9EP3z7BT+5lY5SFhsqGjpgW5DY/i3mK4M9DTBNz3ErMi8BWYEfI3L0d8GIbGmcdFAS1uIRGjA==",
+      "license": "ISC",
+      "peerDependencies": {
+        "react": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0"
+      }
+    },
     "node_modules/queue-microtask": {
       "version": "1.2.3",
       "resolved": "https://registry.npmjs.org/queue-microtask/-/queue-microtask-1.2.3.tgz",