Fix language setting not being saved to database on admin settings page

- Added default_language field to general settings state in SettingsPage
- Replaced LanguageSelector component with simple select dropdown on settings page
- Fixed public settings endpoint to read general_default_language from database
- Language setting now properly saved when clicking Save Settings button
- Setting is correctly used by gallery login page and legal pages

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

backend/package.json

@@ -6,34 +6,39 @@
   "scripts": {
     "start": "node server.js",
     "dev": "nodemon server.js",
-    "migrate": "node migrations/init.js",
+    "migrate": "node migrations/run-migrations.js",
     "test": "jest",
     "lint": "eslint src/"
   },
   "dependencies": {
-    "express": "^4.18.2",
-    "express-rate-limit": "^6.7.0",
-    "helmet": "^7.0.0",
+    "archiver": "^5.3.1",
+    "bcrypt": "^5.1.0",
+    "chokidar": "^3.5.3",
     "cors": "^2.8.5",
     "dotenv": "^16.0.3",
-    "bcrypt": "^5.1.0",
+    "express": "^4.18.2",
+    "express-rate-limit": "^6.7.0",
+    "express-validator": "^7.0.1",
+    "helmet": "^7.0.0",
+    "i18next": "^25.3.1",
+    "i18next-browser-languagedetector": "^8.2.0",
+    "i18next-http-backend": "^3.0.2",
+    "joi": "^17.9.1",
     "jsonwebtoken": "^9.0.0",
+    "knex": "^2.4.2",
     "multer": "^1.4.5-lts.1",
-    "sharp": "^0.32.0",
-    "chokidar": "^3.5.3",
     "node-cron": "^3.0.2",
     "nodemailer": "^6.9.1",
-    "archiver": "^5.3.1",
+    "react-i18next": "^15.6.0",
+    "sharp": "^0.32.0",
     "sqlite3": "^5.1.6",
-    "knex": "^2.4.2",
-    "joi": "^17.9.1",
-    "winston": "^3.8.2",
-    "express-validator": "^7.0.1"
+    "uuid": "^11.1.0",
+    "winston": "^3.8.2"
   },
   "devDependencies": {
-    "nodemon": "^2.0.22",
+    "eslint": "^8.40.0",
     "jest": "^29.5.0",
-    "supertest": "^6.3.3",
-    "eslint": "^8.40.0"
+    "nodemon": "^2.0.22",
+    "supertest": "^6.3.3"
   }
 }