Fix NATS reconnect handling: retry forever instead of giving up after ~2min

Fix NATS reconnect handling: retry forever instead of giving up after ~2min

nats-py's default max_reconnect_attempts (60 * 2s) meant a long-enough NATS
outage would leave worker.py's per-plugin consumer threads permanently
stuck with no recovery path - unlike the AsyncBroker path used by
action_worker.py, they had no closed_cb to notice and react to a permanent
disconnect. Setting max_reconnect_attempts=-1 makes nats-py retry
indefinitely instead; confirmed via a local test that a plugin thread
survives a NATS restart and resumes receiving messages afterward without
any restart of its own. Also bumps connect_timeout from nats-py's 2s
default to 10s, since munin (a Pi Zero-class host) observed transient
connect timeouts when ~40 plugin threads dialed in simultaneously at
startup under the tighter default.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>