* Add lightweight event loop watchdog monitoring
- Thread-based watchdog detects event loop hangs >15s
- Runs independently, won't interfere with normal operation
- Disabled in test environments
- Minimal overhead, just heartbeat checks every 5s
* actually test it
* Add test script to validate watchdog detects hangs
Run with: uv run python test_watchdog_hang.py
Tests:
- Normal operation (no false positives)
- Short blocks under threshold (no alerts)
- Long blocks over threshold (correctly alerts)
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