refactor: 重构 AgentScope ReAct Runner 与事件处理

- 重构 runtime/runner.py 实现 ReAct Agent 核心逻辑
- 更新事件编码器与存储机制
- 优化 prompt 系统与 tool 调用
- 调整 agent service 与 repository 配合

backend/src/v1/friendships/repository.py

@@ -53,6 +53,12 @@ class FriendshipRepository(Protocol):
         """Get friendship by ID."""
         ...
 
+    async def get_friendships_by_ids(
+        self, friendship_ids: list[UUID]
+    ) -> dict[UUID, Friendship]:
+        """Batch get friendships by IDs."""
+        ...
+
     async def get_inbox_messages_for_user(
         self, user_id: UUID, status: InboxMessageStatus | None = None
     ) -> list[InboxMessage]:
@@ -214,6 +220,28 @@ class SQLAlchemyFriendshipRepository(BaseRepository[Friendship]):
             )
             raise
 
+    async def get_friendships_by_ids(
+        self, friendship_ids: list[UUID]
+    ) -> dict[UUID, Friendship]:
+        if not friendship_ids:
+            return {}
+        try:
+            unique_ids = list(dict.fromkeys(friendship_ids))
+            stmt = (
+                select(Friendship)
+                .where(Friendship.id.in_(unique_ids))
+                .where(Friendship.deleted_at.is_(None))
+            )
+            result = await self._session.execute(stmt)
+            friendships = list(result.scalars().all())
+            return {friendship.id: friendship for friendship in friendships}
+        except SQLAlchemyError:
+            logger.exception(
+                "Failed to get friendships by ids",
+                friendship_ids=[str(i) for i in friendship_ids],
+            )
+            raise
+
     async def get_inbox_messages_for_user(
         self, user_id: UUID, status: InboxMessageStatus | None = None
     ) -> list[InboxMessage]: