refactor(llm): centralize usage persistence

next/backend/features/accounts/repository.py

@@ -226,27 +226,6 @@ class AccountRepository:
     def delete_profile(connection: sqlite3.Connection, user_id: int) -> None:
         connection.execute("DELETE FROM birth_profiles WHERE user_id = ?", (user_id,))
 
-    @staticmethod
-    def usage_today(connection: sqlite3.Connection, user_id: int, usage_date: str) -> int:
-        row = connection.execute(
-            """
-            SELECT successful_calls FROM llm_usage_daily
-            WHERE user_id = ? AND usage_date = ?
-            """,
-            (user_id, usage_date),
-        ).fetchone()
-        return int(row["successful_calls"]) if row else 0
-
-    @staticmethod
-    def usage_for_users(connection: sqlite3.Connection, usage_date: str) -> dict[int, int]:
-        return {
-            int(row["user_id"]): int(row["successful_calls"])
-            for row in connection.execute(
-                "SELECT user_id, successful_calls FROM llm_usage_daily WHERE usage_date = ?",
-                (usage_date,),
-            )
-        }
-
     @staticmethod
     def list_memberships(connection: sqlite3.Connection) -> tuple[MembershipAccount, ...]:
         rows = connection.execute(