feat: add WebRTC connection monitoring tools

Add real-time WebRTC connection monitoring for testing video calling apps.
Monitors real RTCPeerConnection instances and collects connection statistics.

New tools:
- browser_start_webrtc_monitoring: Enable monitoring and stats collection
- browser_get_webrtc_connections: List connections with state filtering
- browser_get_webrtc_stats: Detailed stats (bitrate, packet loss, jitter, RTT)
- browser_stop_webrtc_monitoring: Stop stats polling, preserve data
- browser_clear_webrtc_data: Clear captured connection data

Implementation:
- Intercepts RTCPeerConnection constructor via page.addInitScript()
- Captures state changes via page.exposeFunction() callbacks
- Collects stats via page.evaluate() calling getStats()
- Tab-level storage with Context aggregation (same pattern as notifications)
- Configurable stats polling interval (default 1s)

Use cases:
- Test WebRTC call quality in real-time
- Monitor connection states and failures
- Analyze bandwidth, packet loss, frame rates

tests/capabilities.spec.ts

@@ -22,6 +22,7 @@ test('test snapshot tool list', async ({ client }) => {
     'browser_clear_device_motion',
     'browser_clear_device_orientation',
     'browser_clear_injections',
+    'browser_clear_webrtc_data',
     'browser_clear_notifications',
     'browser_clear_permissions',
     'browser_clear_requests',
@@ -43,6 +44,8 @@ test('test snapshot tool list', async ({ client }) => {
     'browser_file_upload',
     'browser_get_artifact_paths',
     'browser_get_requests',
+    'browser_get_webrtc_connections',
+    'browser_get_webrtc_stats',
     'browser_grant_permissions',
     'browser_handle_dialog',
     'browser_handle_notification',
@@ -80,8 +83,10 @@ test('test snapshot tool list', async ({ client }) => {
     'browser_snapshot',
     'browser_start_recording',
     'browser_start_request_monitoring',
+    'browser_start_webrtc_monitoring',
     'browser_status',
     'browser_stop_recording',
+    'browser_stop_webrtc_monitoring',
     'browser_tab_close',
     'browser_tab_list',
     'browser_tab_new',