Bug Description

Dashboard video feed freezes permanently when frame acknowledgments fail (network timeout, connection issues) with no error messages or recovery.

Root Cause

The screencast protocol uses a request-acknowledgment system where the browser waits for an acknowledgment before sending the next frame. The current code uses sendMayFail() which silently swallows all errors, leaving users with a frozen video and no indication of what went wrong.

Reproduction Steps

1. Start Playwright Dashboard with screencast enabled
2. Open a page and start viewing the video feed
3. Simulate one of these conditions:
   • Network timeout: Artificially delay the network connection during frame ack
   • High latency: Use a network throttling tool (e.g., Chrome DevTools Network tab)
   • Connection interruption: Briefly disconnect network while screencast is active
   • Session termination: Close browser session while screencast callback is pending
4. Expected: Error message shown, or video recovers gracefully
5. Actual: Video feed freezes permanently with no error or recovery

Affected Scenarios

• Network timeouts between Dashboard and browser
• Browser session terminated while screencast active
• CDP/protocol connection issues
• High latency connections

User Impact

• Video feed stops updating permanently
• No error message shown
• No recovery mechanism - requires full restart
• Users don't know if it's a bug or intentional pause

Technical Details

• Browser sends frame → waits for ack → sends next frame
• If ack fails, browser never sends next frame
• sendMayFail() hides these failures completely