feat(user): implement user restrictions

## APIs Restricted for Restricted Users

A restricted user is blocked from performing the following actions, and will typically receive a `403 Forbidden` error:

*   **Chat & Notifications:**
    *   Sending any chat messages (public or private).
    *   Joining or leaving chat channels.
    *   Creating new PM channels.
*   **User Profile & Content:**
    *   Uploading a new avatar.
    *   Uploading a new profile cover image.
    *   Changing their username.
    *   Updating their userpage content.
*   **Scores & Gameplay:**
    *   Submitting scores in multiplayer rooms.
    *   Deleting their own scores (to prevent hiding evidence of cheating).
*   **Beatmaps:**
    *   Rating beatmaps.
    *   Taging beatmaps.
*   **Relationship:**
    *   Adding friends or blocking users.
    *   Removing friends or unblocking users.
*   **Teams:**
    *   Creating, updating, or deleting a team.
    *   Requesting to join a team.
    *   Handling join requests for a team they manage.
    *   Kicking a member from a team they manage.
*   **Multiplayer:**
    *   Creating or deleting multiplayer rooms.
    *   Joining or leaving multiplayer rooms.

## What is Invisible to Normal Users

*   **Leaderboards:**
    *   Beatmap leaderboards.
    *   Multiplayer (playlist) room leaderboards.
*   **User Search/Lists:**
    *   Restricted users will not appear in the results of the `/api/v2/users` endpoint.
    *   They will not appear in the list of a team's members.
*   **Relationship:**
    *   They will not appear in a user's friend list (`/friends`).
*   **Profile & History:**
    *   Attempting to view a restricted user's profile, events, kudosu history, or score history will result in a `404 Not Found` error, effectively making their profile invisible (unless the user viewing the profile is the restricted user themselves).
*   **Chat:**
    *   Normal users cannot start a new PM with a restricted user (they will get a `404 Not Found` error).
*   **Ranking:**
    *   Restricted users are excluded from any rankings.

### How to Restrict a User

Insert into `user_account_history` with `type=restriction`.

```sql
-- length is in seconds
INSERT INTO user_account_history (`description`, `length`, `permanent`, `timestamp`, `type`, `user_id`) VALUE ('some description', 86400, 0, '2025-10-05 01:00:00', 'RESTRICTION', 1);
```

---

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

app/router/v2/room.py

@@ -143,6 +143,9 @@ async def create_room(
     current_user: ClientUser,
     redis: Redis,
 ):
+    if await current_user.is_restricted(db):
+        raise HTTPException(status_code=403, detail="Your account is restricted from multiplayer.")
+
     user_id = current_user.id
     db_room = await create_playlist_room_from_api(db, room, user_id)
     await _participate_room(db_room.id, user_id, db_room, db, redis)
@@ -189,6 +192,9 @@ async def delete_room(
     room_id: Annotated[int, Path(..., description="房间 ID")],
     current_user: ClientUser,
 ):
+    if await current_user.is_restricted(db):
+        raise HTTPException(status_code=403, detail="Your account is restricted from multiplayer.")
+
     db_room = (await db.exec(select(Room).where(Room.id == room_id))).first()
     if db_room is None:
         raise HTTPException(404, "Room not found")
@@ -211,6 +217,9 @@ async def add_user_to_room(
     redis: Redis,
     current_user: ClientUser,
 ):
+    if await current_user.is_restricted(db):
+        raise HTTPException(status_code=403, detail="Your account is restricted from multiplayer.")
+
     db_room = (await db.exec(select(Room).where(Room.id == room_id))).first()
     if db_room is not None:
         await _participate_room(room_id, user_id, db_room, db, redis)
@@ -235,6 +244,9 @@ async def remove_user_from_room(
     current_user: ClientUser,
     redis: Redis,
 ):
+    if await current_user.is_restricted(db):
+        raise HTTPException(status_code=403, detail="Your account is restricted from multiplayer.")
+
     db_room = (await db.exec(select(Room).where(Room.id == room_id))).first()
     if db_room is not None:
         participated_user = (