refactor(llm): centralize usage persistence

next/backend/llm/repository.py

@@ -12,6 +12,16 @@ class LLMRepository:
         ).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 active_today(connection: sqlite3.Connection, user_id: int, day_prefix: str) -> int:
         row = connection.execute(