feat: add PWA inspection and download tools

Add browser_pwa_info (read-only) to detect and report PWA metadata
including manifest, service worker state, and CacheStorage contents.

Add browser_pwa_download to save complete PWA packages with manifest,
icons, service worker scripts, and cached resources to disk.

tests/capabilities.spec.ts

@@ -75,6 +75,8 @@ test('test snapshot tool list', async ({ client }) => {
     'browser_network_requests',
     'browser_pause_recording',
     'browser_press_key',
+    'browser_pwa_download',
+    'browser_pwa_info',
     'browser_recording_status',
     'browser_request_monitoring_status',
     'browser_resize',