规范 UI 语义建议错误提示

将 LLM 缺少工具调用、参数解析和结果校验失败统一标记为响应无效

保留详细校验原因供排障

apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/ui_design_suggestion.rs

@@ -191,17 +191,17 @@ pub(crate) async fn suggest_ui_design_semantic_impl(
         .find(|call| call.name == "suggest_ui_design_semantics")
         .ok_or_else(|| {
             eprintln!("ui_design_suggestion.error stage=parse_tool_call reason=missing_tool_call");
-            "LLM 未返回 suggest_ui_design_semantics 工具调用".to_string()
+            "LLM 响应无效（详情：未返回 suggest_ui_design_semantics 工具调用）".to_string()
         })?;
     let suggestions = serde_json::from_str::<UIDesignSuggestion>(&call.arguments)
         .map_err(|error| {
             eprintln!("ui_design_suggestion.error stage=parse_arguments error={error}");
-            format!("UI 语义建议工具参数无效：{error}")
+            format!("LLM 响应无效（详情：UI 语义建议工具参数无效：{error}）")
         })?
         .ui_designs;
     validate_suggestions(&suggestions, &ids).map_err(|error| {
         eprintln!("ui_design_suggestion.error stage=validate_result error={error}");
-        error
+        format!("LLM 响应无效（详情：{error}）")
     })?;
     // TODO: future single-page policy may reject multiple Page suggestions.
     Ok(suggestions)