refactor: 简化 AgentScope 运行时模块与事件处理

- 移除冗余的 user_token 参数传递
- 重构 tool.result 事件使用 ToolAgentOutput 模型
- 重构 text.end 事件使用 WorkerAgentOutput 模型
- 简化 store 模块的 tool result 处理逻辑
- 更新 router/service 适配新事件结构
- 清理废弃的测试文件与设计文档
- 新增 AgentRuns 多模态存储设计文档

backend/tests/unit/schemas/messages/test_chat_message_schema.py

@@ -0,0 +1,29 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime
+from uuid import uuid4
+
+from schemas.messages.chat_message import AgentChatMessage
+
+
+def test_agent_chat_message_schema_matches_messages_columns() -> None:
+    now = datetime.now(UTC)
+    payload = {
+        "id": uuid4(),
+        "seq": 3,
+        "role": "assistant",
+        "content": "hello",
+        "metadata": {"run_id": "run-1"},
+        "timestamp": now,
+    }
+
+    message = AgentChatMessage.model_validate(payload)
+
+    assert message.seq == 3
+    assert message.role == "assistant"
+    assert message.content == "hello"
+    assert message.metadata is not None
+    if isinstance(message.metadata, dict):
+        assert message.metadata == {"run_id": "run-1"}
+    else:
+        assert message.metadata.model_dump(exclude_none=True) == {"run_id": "run-1"}