Day/Night Planner

Pick your tasks, set your start and sleep hours, and the planner tells you whether you'll make it home before the demons wake.

Audit pending. Phase 0 calibration constants are still TODO; the planner is disabled until wxq fills in real values.

Calibration constants pull from src/data/constants.ts. If you see an "audit pending" message, the Phase 0 audit has not yet been completed — see disclaimer.