fix: skip FunctionCallingConfig when only native tools are present (#7407)

* fix: skip FunctionCallingConfig when only native tools are present

When native tools (google_search, url_context) are enabled without any
function_declarations, _prepare_query_config was still creating a
FunctionCallingConfig, which makes Gemini API return 400 INVALID_ARGUMENT.

Now we only set tool_config when tool_list actually contains
function_declarations.

Fixes #7406

* style: ruff format

Author: he-yufeng

astrbot/core/provider/sources/gemini_source.py

@@ -215,7 +215,8 @@ async def _prepare_query_config(
             ]
 
         tool_config = None
-        if tools and tool_list:
+        has_func_decl = tool_list and any(t.function_declarations for t in tool_list)
+        if has_func_decl:
             tool_config = types.ToolConfig(
                 function_calling_config=types.FunctionCallingConfig(
                     mode=(