Adds QuietHours config section (start/end as HH:MM local time). The loop's
gatherer checks the window each tick: if now falls within [start, end), the
State.QuietHours flag is set to true regardless of the config fact (which
the voice toggle writes independently). Both sources activate quiet —
schedule AND toggle.
Handles midnight-crossing windows (23:00-08:00). The gate already reads
State.QuietHours for care nudge suppression — no gate change needed.
kami