Add timeout protection and silence ping messages in streaming
- Add 10-minute timeout to prevent infinite hangs in streaming loops
- Silence 'ping' keepalive messages (log at debug level only)
- Apply to both notification processing and synthesis streams
- Prevents logs from being spammed with ping messages
- Stream will break after 600 seconds if agent doesn't send 'done'
This fixes the issue where streaming would hang indefinitely
when agents get stuck or don't complete properly.
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