Register the weekly suggestions schedule (Feature 20)

suggest.Service.WeeklySchedule fires at the household suggestions_dow and
suggestions_time (default Sunday 08:00) with period key
suggestions_weekly:YYYY-Www and starts a scheduled batch through the same
service and job as the API, via the new StartScheduledBatch(week).
StartBatch now refuses the scheduled trigger.

new_suggestions is still emitted only where Feature 19 put it, in the
transaction that stores a batch's Side quests. A scheduled batch is now
keyed new_suggestions:YYYY-Www by the week carried in its job, so a
batch caught up late keeps its own week's key; a manual batch stays keyed
by its id. The title counts the new Side quests. A batch whose AI call
fails stores nothing and sends nothing; the failure is in ai_runs.

Fake-clock tests in internal/scheduler cover one batch and one
notification per week, settings-driven fire time, AI failure, restart,
late catch-up and a batch already under way.

Maestro task 459aab71-5c3d-4853-9855-236a3602b1e0

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

cmd/server/main.go

@@ -192,6 +192,9 @@ func run(cfg config.Config, logger *slog.Logger) error {
 	if err != nil {
 		return err
 	}
+	if err := sched.Register(suggestSvc.WeeklySchedule()); err != nil {
+		return err
+	}
 
 	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, search, ai, chatSvc, dinnerSvc, suggestSvc, planSvc, shopSvc, googleSvc, pushSvc, ideasSvc, runner, photos, frontend.Assets())
 	if err != nil {