Move nano schedules beside the control plane #33

Adds a daily noon nano heartbeat and repairs Callie’s five-day shot reminder. Both timers now run on homura beside the loopback-only control API; the shot cadence is re-anchored to 2026-09-06 and next fires 2026-09-11. Removes the unreachable reef webhook timer. Includes bounded retries/start limits. Validated with Nix parsing, date-math checks, generated unit/script inspection, and a full homura toplevel build.