Re-plan the missed sweep when the panel adopts a time zone

The scheduler loaded settings once per cycle and slept on them until the
old rollover, so a zone adopted from Home Assistant after start-up left a
UTC host sweeping at UTC midnight (20:00 in New York), marking quests
missed hours early.

`MissedSweepScheduler.settings_changed` now wakes the sleeping loop when
the stored zone or rollover time differs from the one it planned with;
the panel's household clock calls it after adopting a reported zone.
Before sweeping, the loop re-reads the settings and re-plans instead if
they no longer match its plan.

Tests: the scheduler re-plans for New York midnight when a panel request
adopts the zone mid-sleep, and skips a stale sweep when the zone changed
without a wake-up.  The admin-precedence and invalid-header tests now
prove adoption first, and the SSE client test asserts the timezone header
rides beside the Authorization header.

Task: 6351b36d-0eef-4e7d-bf5a-96b754cbc883

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/routes_panel.py

@@ -198,7 +198,9 @@ async def _household_clock(
     Home Assistant's ``time_zone`` in :data:`PANEL_TIMEZONE_HEADER`;
     until the admin chooses a zone it is adopted and persisted
     (:func:`nestquest_core.settings_store.adopt_reported_timezone`), so
-    the scheduler and the admin plane follow it too.  An invalid
+    the admin plane follows it too, and the already-sleeping missed-sweep
+    scheduler is told (:meth:`MissedSweepScheduler.settings_changed`) so
+    it re-plans for the household rollover.  An invalid
     reported zone is logged and ignored — the panel keeps serving on
     the stored settings.
     """
@@ -208,6 +210,7 @@ async def _household_clock(
             settings = await core_settings_store.adopt_reported_timezone(
                 database, reported
             )
+            request.app.state.sweep_scheduler.settings_changed(settings)
         except ValueError:
             LOGGER.warning(
                 "Ignoring invalid %s header value %r",