refactor(common-config): consolidate hooks and migrate Gemini to ENV format

- Delete redundant wrapper hooks (useCommonConfigSnippet, useGeminiCommonConfig)
- Change Gemini common config from JSON to ENV format (.env style)
- Add backend validation with forbidden keys filtering (GEMINI_API_KEY, GOOGLE_GEMINI_BASE_URL)
- Fix localStorage migration to skip empty parsed snippets
- Add error handling for silent JSON parse failures
- Clean up debug logs and unused types

src/components/DeepLinkImportDialog.tsx

@@ -53,15 +53,12 @@ export function DeepLinkImportDialog() {
     const unlistenImport = listen<DeepLinkImportRequest>(
       "deeplink-import",
       async (event) => {
-        console.log("Deep link import event received:", event.payload);
-
         // If config is present, merge it to get the complete configuration
         if (event.payload.config || event.payload.configUrl) {
           try {
             const mergedRequest = await deeplinkApi.mergeDeeplinkConfig(
               event.payload,
             );
-            console.log("Config merged successfully:", mergedRequest);
             setRequest(mergedRequest);
           } catch (error) {
             console.error("Failed to merge config:", error);