feat: add plugin extension pages (iframe rendering, Page SDK, security hardening, i18n)

Co-Authored-By: Typer_Body <mcjiekejiemi@163.com>

src/langbot/pkg/plugin/handler.py

@@ -939,6 +939,11 @@ class RuntimeConnectionHandler(handler.Handler):
             timeout=20,
         )
         asset_file_key = result['file_file_key']
+        if not asset_file_key:
+            return {
+                'asset_base64': '',
+                'mime_type': '',
+            }
         mime_type = result['mime_type']
         asset_bytes = await self.read_local_file(asset_file_key)
         await self.delete_local_file(asset_file_key)
@@ -947,6 +952,30 @@ class RuntimeConnectionHandler(handler.Handler):
             'mime_type': mime_type,
         }
 
+    async def handle_page_api(
+        self,
+        plugin_author: str,
+        plugin_name: str,
+        page_id: str,
+        endpoint: str,
+        method: str,
+        body: Any = None,
+    ) -> dict[str, Any]:
+        """Forward a page API call to the plugin via runtime."""
+        result = await self.call_action(
+            LangBotToRuntimeAction.PAGE_API,
+            {
+                'plugin_author': plugin_author,
+                'plugin_name': plugin_name,
+                'page_id': page_id,
+                'endpoint': endpoint,
+                'method': method,
+                'body': body,
+            },
+            timeout=30,
+        )
+        return result
+
     async def cleanup_plugin_data(self, plugin_author: str, plugin_name: str) -> None:
         """Cleanup plugin settings and binary storage"""
         # Delete plugin settings