style: format frontend with prettier

Mechanical one-shot pass of pnpm format over src/, tests/, tools/, and
root configs. No functional changes; build and type-check verified.

playwright.config.ts

@@ -1,4 +1,4 @@
-import { defineConfig, devices } from '@playwright/test';
+import { defineConfig, devices } from '@playwright/test'
 
 /**
  * Read environment variables from file.
@@ -76,4 +76,4 @@ export default defineConfig({
   //   url: 'http://localhost:3000',
   //   reuseExistingServer: !process.env.CI,
   // },
-});
+})