fix: inject agent_id into system prompt for all WS handlers + enhance schedule_delete

- All 5 WS handlers (lingxi/feishu/orange/suyao/tiantian) now inject agent_id
  into LLM system prompt so agents know their own ID for schedule_list calls
- schedule_delete_tool now supports agent_id parameter for ownership checks
  and bulk delete by agent_id
- SCHEDULE_DELETE_SCHEMA updated: required fields now empty, supports
  both schedule_id and agent_id params

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/services/feishu_ws_handler.py

@@ -176,7 +176,11 @@ async def _handle_message_async(data):
 
         config = AgentConfig(
             name=agent.name or "agent",
-            system_prompt=system_prompt,
+            system_prompt=system_prompt + (
+                f"\n\n## 系统信息\n"
+                f"你的 Agent ID 是: {agent.id}\n"
+                f"在调用 schedule_list、schedule_delete 等工具时，使用此 ID 作为 agent_id 参数。"
+            ),
             llm=AgentLLMConfig(
                 model=model,
                 provider=provider,