Add customizable home dashboard with per-user pinned apps

- Users can pin/unpin any available service on their home page via a
  Customize mode; preferences persisted via PATCH /api/users/me/preferences
- Time-aware greeting renders the user's display name through React JSX
  (HTML-escaped by design — no dangerouslySetInnerHTML used)
- Added dashboard_app_ids JSON column to users table (migration c7e8f9a0b1d2)
- /settings now routes to a placeholder page

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

backend/app/routers/users.py

@@ -1,8 +1,10 @@
 from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.database import get_db
 from app.deps import get_current_user
 from app.models.user import User
-from app.schemas.user import UserOut
+from app.schemas.user import DashboardPrefsOut, DashboardPrefsUpdate, UserOut
 
 router = APIRouter()
 
@@ -10,3 +12,20 @@ router = APIRouter()
 @router.get("/me", response_model=UserOut)
 async def get_me(current_user: User = Depends(get_current_user)):
     return current_user
+
+
+@router.get("/me/preferences", response_model=DashboardPrefsOut)
+async def get_preferences(current_user: User = Depends(get_current_user)):
+    return DashboardPrefsOut(app_ids=current_user.dashboard_app_ids or [])
+
+
+@router.patch("/me/preferences", response_model=DashboardPrefsOut)
+async def update_preferences(
+    body: DashboardPrefsUpdate,
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    current_user.dashboard_app_ids = body.app_ids
+    await db.commit()
+    await db.refresh(current_user)
+    return DashboardPrefsOut(app_ids=current_user.dashboard_app_ids or [])