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/ranking.py

@@ -99,6 +99,7 @@ async def get_team_ranking(
                     UserStatistics.mode == ruleset,
                     UserStatistics.pp > 0,
                     col(UserStatistics.user).has(col(User.team_membership).has(col(TeamMember.team_id) == team.id)),
+                    ~User.is_restricted_query(col(UserStatistics.user_id)),
                 )
             )
         ).all()
@@ -249,6 +250,7 @@ async def get_country_ranking(
                     UserStatistics.pp > 0,
                     col(UserStatistics.user).has(country_code=country),
                     col(UserStatistics.user).has(is_active=True),
+                    ~User.is_restricted_query(col(UserStatistics.user_id)),
                 )
             )
         ).all()
@@ -363,7 +365,14 @@ async def get_user_ranking(
     total_count = total_count_result.one()
 
     statistics_list = await session.exec(
-        select(UserStatistics).where(*wheres).order_by(order_by).limit(50).offset(50 * (page - 1))
+        select(UserStatistics)
+        .where(
+            *wheres,
+            ~User.is_restricted_query(col(UserStatistics.user_id)),
+        )
+        .order_by(order_by)
+        .limit(50)
+        .offset(50 * (page - 1))
     )
 
     # 转换为响应格式