Fixes#3033
The container logs WebSocket connection was closing after approximately
60 seconds of inactivity with error code 1006 (abnormal closure).
This required users to manually refresh the page to re-establish the
connection, making it difficult to monitor containers that produce logs
infrequently.
Changes:
- Added WebSocket ping mechanism sending ping frames every 45 seconds
- Ensures connection stays alive indefinitely during periods of no log activity
- Properly cleanup ping intervals on connection close (3 locations)
- Prevents memory leaks by clearing intervals on error and close events
The browser automatically responds with pong frames, keeping the
connection alive without requiring any client-side changes.
