Push the week's plan to Google Calendar (Feature 16)

POST /api/v1/plans/{weekStart}/push-calendar writes one event per plan
day to the chosen calendar: "Dinner: {name}" from the household dinner
time for 60 minutes in the household zone, with the dinner name,
"Start by {time}" for crock-pot dinners and the
{MEALQUEST_PUBLIC_URL}/dinner/{id} link. Event ids are the lowercase
base32hex SHA-256 of "mealquest|{weekStart}|{date}"; each event is
inserted, and a 409 updates it instead.

gcal.Service.PushEvents does the Calendar writes under the account lock,
with the same redaction as listing. plan.Service.Push records a push only
when every event was written: the plan becomes synced with
calendar_synced_at and each day stores its event id. A partial failure
records nothing; a plan edited mid-push is 409 plan_changed.

A swap, or a redraft to another dinner, clears the day's
calendar_event_id, so the next push writes just those days; a push with
none pending writes every day again.

No calendar chosen is 409 no_calendar; a deleted or read-only chosen
calendar is 409 calendar_unavailable; a refused grant is 502
reconnect_required, leaving the connection as it is.

Maestro task 5885d2b1-cf06-44ff-abf3-242d7763c3c9.

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

migrations/queries/plans.sql

@@ -7,7 +7,7 @@ WHERE week_start = ?;
 -- name: ListPlanDays :many
 -- The days of plan plan_id with their dinners, Monday first. A day with
 -- no dinner is left out.
-SELECT plan_days.date, plan_days.is_new, sqlc.embed(dinners)
+SELECT plan_days.date, plan_days.is_new, plan_days.calendar_event_id, sqlc.embed(dinners)
 FROM plan_days
 JOIN dinners ON dinners.id = plan_days.dinner_id
 WHERE plan_days.plan_id = ?
@@ -25,20 +25,39 @@ SET status = ?, ai_note = ?, revision = revision + 1, updated_at = ?
 WHERE id = ?;
 
 -- name: PutPlanDay :exec
--- Plans dinner_id on date of plan_id, keeping the day's calendar event id
--- when the day exists.
+-- Plans dinner_id on date of plan_id. An existing day keeps its calendar
+-- event id while its dinner stays the same; a new dinner clears it, since
+-- Calendar no longer shows the day as planned.
 INSERT INTO plan_days (id, plan_id, date, dinner_id, is_new, created_at, updated_at)
 VALUES (?, ?, ?, ?, ?, ?, ?)
 ON CONFLICT (plan_id, date) DO UPDATE
-SET dinner_id = excluded.dinner_id, is_new = excluded.is_new, updated_at = excluded.updated_at;
+SET dinner_id = excluded.dinner_id, is_new = excluded.is_new,
+	calendar_event_id = CASE WHEN plan_days.dinner_id IS excluded.dinner_id THEN plan_days.calendar_event_id END,
+	updated_at = excluded.updated_at;
 
 -- name: SwapPlanDay :execrows
--- Plans dinner_id on an existing day of plan_id; a date the plan does not
--- have is left as it is (0 rows).
+-- Plans dinner_id on an existing day of plan_id, clearing its calendar
+-- event id since Calendar no longer shows the day as planned; a date the
+-- plan does not have is left as it is (0 rows).
 UPDATE plan_days
-SET dinner_id = ?, is_new = ?, updated_at = ?
+SET dinner_id = ?, is_new = ?, calendar_event_id = NULL, updated_at = ?
 WHERE plan_id = ? AND date = ?;
 
+-- name: SetPlanDayCalendarEvent :execrows
+-- Records that the event calendar_event_id on Calendar shows date of
+-- plan_id as planned.
+UPDATE plan_days
+SET calendar_event_id = ?, updated_at = ?
+WHERE plan_id = ? AND date = ?;
+
+-- name: MarkWeekPlanSynced :execrows
+-- Records a Push to Calendar of plan id as it was at revision: the plan
+-- becomes synced. A plan edited since (another revision) is left as it is
+-- (0 rows).
+UPDATE week_plans
+SET status = 'synced', calendar_synced_at = ?, updated_at = ?
+WHERE id = ? AND revision = ?;
+
 -- name: MarkWeekPlanEdited :exec
 -- Records an edit of plan id, raising its revision: a synced plan becomes
 -- changed, any other keeps its status.