feat(admin): enhance editor UI (links, image captions) & fix categories

Added animated auto-opening link modal, custom image node with isolated caption deletion, fixed single-select category data binding, improved featured image layout, and updated README.

frontend/package-lock.json

@@ -19,6 +19,7 @@
         "lucide-react": "0.522.0",
         "react": "^18.3.1",
         "react-dom": "^18.3.1",
+        "react-hook-form": "^7.88.0",
         "react-multi-date-picker": "^4.5.2",
         "react-router-dom": "^6.26.2",
         "react-select": "^5.10.2",
@@ -4484,6 +4485,22 @@
         "react-dom": ">=16.8.0"
       }
     },
+    "node_modules/react-hook-form": {
+      "version": "7.88.0",
+      "resolved": "https://registry.npmjs.org/react-hook-form/-/react-hook-form-7.88.0.tgz",
+      "integrity": "sha512-QRaLOWhX93YCnMiRfnOFRSwWXZNt8qhm2JTZwypoDvKpSffTJHmpzMXt8U6PV5UThvL3IiiLDUWe2nHMtz6Mmw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=18.0.0"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/react-hook-form"
+      },
+      "peerDependencies": {
+        "react": "^16.8.0 || ^17 || ^18 || ^19"
+      }
+    },
     "node_modules/react-is": {
       "version": "16.13.1",
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-16.13.1.tgz",