Phase 3-4: Goals AI planner, Team tasks, Push notifications, i18n (CZ/HE/RU/UA)

- Goals CRUD API + AI study plan generator + progress reports
- Goals frontend page with progress bars
- Team tasks: assign, transfer, collaborate endpoints
- Push notifications: web-push, VAPID, subscribe/send
- i18n: 4 languages (cs, he, ru, ua) translation files
- notifications.js + goals.js routes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/package.json

@@ -25,7 +25,8 @@
     "ioredis": "^5.10.1",
     "pg": "^8.20.0",
     "redis": "^5.11.0",
-    "uuid": "^13.0.0"
+    "uuid": "^13.0.0",
+    "web-push": "^3.6.7"
   },
   "devDependencies": {
     "nodemon": "^3.1.14"