fix(grokbuild): complete proxy and deep-link integrations (#5677)

* fix(grokbuild): complete proxy integration

* fix(deeplink): preview GrokBuild configs safely

* test(app): stabilize provider integration suite

* fix(grokbuild): address review feedback

* fix(grokbuild): resolve remaining review findings

* fix(grokbuild): use native sessions and harden previews

tests/msw/handlers.ts

@@ -44,6 +44,7 @@ export const handlers = [
   http.post(`${TAURI_ENDPOINT}/get_skills_migration_result`, () =>
     success(null),
   ),
+  http.post(`${TAURI_ENDPOINT}/list_profiles`, () => success([])),
   http.post(`${TAURI_ENDPOINT}/get_providers`, async ({ request }) => {
     const { app } = await withJson<{ app: AppId }>(request);
     return success(getProviders(app));