feat: 添加 Agent 步骤事件与图片附件功能

- 新增 stepStarted/stepFinished 事件类型支持
- 前端实现图片附件上传和预览功能
- 后端增强工具结果存储和事件处理
- 完善相关单元测试和集成测试

backend/src/services/base/supabase.py

@@ -19,19 +19,14 @@ class SupabaseService(BaseServiceProvider):
 
     async def initialize(self, **_: Any) -> bool:
         try:
-            self._client = create_client(
-                self._settings.url,
-                self._settings.anon_key,
-            )
-            self._admin_client = create_client(
-                self._settings.url,
-                self._settings.service_role_key,
-            )
+            self._init_clients()
             self._set_initialized(True)
             self.logger.info("Supabase service initialized")
             return True
         except Exception as exc:  # noqa: BLE001
-            self.logger.warning("Supabase service initialization failed", error=str(exc))
+            self.logger.warning(
+                "Supabase service initialization failed", error=str(exc)
+            )
             self._client = None
             self._admin_client = None
             self._set_initialized(False)
@@ -51,7 +46,9 @@ class SupabaseService(BaseServiceProvider):
             return {"status": "unhealthy", "details": {"error": "not initialized"}}
         try:
             await asyncio.to_thread(client.auth.get_session)
-            await asyncio.to_thread(admin_client.auth.admin.list_users, page=1, per_page=1)
+            await asyncio.to_thread(
+                admin_client.auth.admin.list_users, page=1, per_page=1
+            )
             return {
                 "status": "healthy",
                 "details": {
@@ -70,17 +67,35 @@ class SupabaseService(BaseServiceProvider):
         return self._require_admin_client()
 
     def _require_client(self) -> Any:
+        if self._client is None or self._admin_client is None:
+            self._init_clients()
+            self._set_initialized(True)
+            self.logger.info("Supabase service lazily initialized")
         client = self._client
         if client is None:
             raise RuntimeError("Supabase client is not initialized")
         return client
 
     def _require_admin_client(self) -> Any:
+        if self._client is None or self._admin_client is None:
+            self._init_clients()
+            self._set_initialized(True)
+            self.logger.info("Supabase service lazily initialized")
         admin_client = self._admin_client
         if admin_client is None:
             raise RuntimeError("Supabase admin client is not initialized")
         return admin_client
 
+    def _init_clients(self) -> None:
+        self._client = create_client(
+            self._settings.url,
+            self._settings.anon_key,
+        )
+        self._admin_client = create_client(
+            self._settings.url,
+            self._settings.service_role_key,
+        )
+
 
 supabase_service: SupabaseService = register_service_instance(
     "supabase", SupabaseService()