Serialise time zone adoption with the missed-sweep scheduler

The wake flag compared an adoption only against the plan the loop last
recorded, so New York -> UTC -> New York during the re-plan read left
the scheduler sleeping on UTC midnight; and an adoption committing
between the pre-sweep check and the sweep still let the stale sweep run.

`MissedSweepScheduler.settings_lock` now serialises the panel's adoption
(write plus `settings_changed`) with the loop's plan read and with its
pre-sweep re-read plus sweep.  It is never held across the wait, and the
loop holds nothing else while acquiring it, so a panel request is at
most delayed by one settings read or one sweep.

`_sleep_unless_woken` now cancels and awaits both child tasks, and
re-raises a failed sleep inside the loop's retry block, so the backoff
runs instead of a sweep and nothing outlives `stop()`.

Tests (all four fail on bcf387d): the successive-zone race, an adoption
issued during the pre-sweep check, a failing sleep, and stop() waiting
for the sleep's cancellation cleanup.

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

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

RELEASE_NOTES.md

@@ -1,56 +1,5 @@
 # NestQuest Release Notes
 
-## Version 0.9.6 — 2026-09-28
-
-### Scope
-
-Patch release carrying the household time-zone fix onto `main` (PR #275, task
-6351b36d "Time zone errors").
-
-### Behaviour
-
-- The Home Assistant integration now reports `hass.config.time_zone` to the API
-  in an `X-NestQuest-Timezone` header on every panel request.
-- While the API's `timezone` setting has never been explicitly chosen
-  (`timezone_configured` false), the API adopts and persists the reported zone
-  (under the settings lock), so the panel's overdue/today calculation, the
-  admin plane and the missed-sweep scheduler are all household-local even when
-  the API host runs UTC. No manual setup is required.
-- The missed-sweep scheduler re-plans immediately when the adopted zone changes
-  while it is sleeping, and re-reads the stored zone before sweeping, so it no
-  longer fires at the old (UTC) rollover.
-- An admin-chosen zone — including an explicit choice of empty (API-host local)
-  — still wins over the reported zone. An invalid reported zone is logged and
-  ignored; the panel keeps serving on the stored settings.
-
-### Requirements
-
-- Home Assistant floor 2024.6.0 (unchanged).
-
-### Breaking changes
-
-- None. The database schema is unchanged at version 9: no migration and no
-  database backup is required for this release.
-- Deployment note: this fix needs BOTH the API service and the HA integration
-  upgraded. The integration supplies the zone and the API adopts it; upgrading
-  only one side leaves the previous behaviour. An install whose `timezone` was
-  previously set — or explicitly cleared to host-local — keeps that choice.
-
-### Known limitations
-
-- If `timezone` is empty and `timezone_configured` is true (an explicit
-  "host local" choice), that choice is respected and the API host's zone (UTC
-  on the standard deployment) still applies until an admin selects a zone in
-  the admin Preferences.
-- A change to Home Assistant's own `time_zone` takes effect after the
-  integration reloads or Home Assistant restarts.
-
-### Rollback
-
-- No schema change: rolling back to 0.9.5 requires no database restore. The API
-  and the integration may be rolled back independently; rolling back only the
-  integration restores the previous stored-setting-only behaviour.
-
 ## Version 0.9.5 — 2026-09-27
 
 ### Scope

custom_components/nestquest/manifest.json

@@ -15,5 +15,5 @@
   "iot_class": "local_polling",
   "issue_tracker": "https://github.com/Maniacs-Mansion/NestQuest/issues",
   "requirements": [],
-  "version": "0.9.6"
+  "version": "0.9.5"
 }

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "nestquest"
-version = "0.9.6"
+version = "0.9.5"
 description = "NestQuest Home Assistant Integration"
 readme = "README.md"
 requires-python = ">=3.11"

uv.lock

@@ -373,7 +373,7 @@ wheels = [
 
 [[package]]
 name = "nestquest"
-version = "0.9.6"
+version = "0.9.5"
 source = { virtual = "." }
 
 [package.dev-dependencies]