Track bot start time via monotonic clock, display as compact
duration (e.g. "up 3d 2h 15m 42s").
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Query CT logs via crt.sh to enumerate SSL certs for domains,
report expired/valid counts, and flag live expired certs.
Uses ThreadPoolExecutor(3) for blocking I/O on RPi5.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>