Replace manual arg parsing with clap derive for the full command set.
Single source of truth for command names, args, and help text.
Add notify_timeout (default 2min) — controls how long after last
response before notifications inject via tmux instead of waiting
for the hook. Separate from idle_timeout (5min) which controls
autonomous prompts.
Improve `poc-daemon status` to show both timers with elapsed/configured
and block reason, replacing the terse one-liner.
Add new Status fields over capnp: idleTimeout, notifyTimeout,
sinceActivity, sinceUser, blockReason.
ExecStart in poc-daemon.service now uses `daemon` subcommand.
Co-Authored-By: ProofOfConcept <poc@bcachefs.org>