refactor: 重构 Tool Result 契约，移除 ui_hints 统一使用 result 字段

- ToolAgentOutput 移除 result_summary 和 ui_hints，统一使用 result 字段
- 日历/用户查找工具移除 ui_hints 输出，改为机器可读的结构化结果
- Agent History 移除 tool 消息的 ui_hints 处理逻辑
- App 版本检查改为 manifest.json 方式，支持多渠道发布
- 更新 settings 配置和测试用例适配新结构

backend/tests/unit/v1/agent/test_utils.py

@@ -16,21 +16,18 @@ class _FakeMessage:
         self.timestamp = datetime.now(timezone.utc)
 
 
-def test_convert_message_to_history_uses_ui_schema_key_for_tool_message() -> None:
+def test_convert_message_to_history_does_not_attach_ui_schema_for_tool_message() -> (
+    None
+):
     message = _FakeMessage(
         role="tool",
-        metadata={
-            "tool_agent_output": {
-                "ui_schema": {"version": "2.0", "root": {"type": "stack"}}
-            }
-        },
+        metadata={"tool_agent_output": {"result": "done"}},
     )
 
     result = convert_message_to_history(message)  # type: ignore[arg-type]
 
-    assert "ui_schema" in result
+    assert "ui_schema" not in result
     assert "uiSchema" not in result
-    assert result["ui_schema"] == {"version": "2.0", "root": {"type": "stack"}}
 
 
 def test_convert_message_to_history_uses_ui_schema_key_for_assistant_message() -> None: