Wire plan_ready, list_ready, new_suggestions and Send to Google Chat

Connect the features to the notification outbox so real events notify,
each stored by the new notify.EmitTx in the transaction of the change it
is about (Wake after commit):

- plan_ready:{weekStart} (/plan) when a draft job stores the AI's draft;
  a redraft shares the key and a manual swap never emits. The title reads
  "Next week's plan is ready" for the coming week.
- list_ready:{weekStart} (/plan/shopping) when a week's Supply run is
  first created, by generate or after Push to Calendar.
- new_suggestions:{batchId} (/discover) when a scheduled or manual batch
  ends done with cards; replenish batches never notify.
- plan.Service.EmitDayOfReminder(date) emits day_of_reminder:{date} for
  the Feature 20 scheduler.

Add POST /api/v1/shopping/{weekStart}/send-chat: shopping.SendToChat posts
the dinners with needed items and a link through chat.PostSupplyRun,
records sent_to_chat_at, and is idempotent per week unless
{"resend": true}. The Supply run's Send to Google Chat button calls it
("Send again" once sent) and shows failures in an ErrorBanner; the unused
Unavailable placeholder is removed.

Task: f0cd9d50-9c11-41be-a945-7bae9f5f28a4

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

internal/shopping/shopping.go

@@ -27,10 +27,12 @@ import (
 	"time"
 
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/skills"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/chat"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/jobs"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/notify"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
 )
 
@@ -95,6 +97,8 @@ type Service struct {
 	st       *store.Store
 	title    Titler
 	titleJob *jobs.Kind[TitleJob]
+	notifier *notify.Service
+	chat     *chat.Service
 	logger   *slog.Logger
 	// now is the clock weeks are ended and current on; tests replace it.
 	now func() time.Time
@@ -104,12 +108,17 @@ type Service struct {
 	// waits for the title jobs in flight to store their titles or fail,
 	// and no title job runs archive_title while a freeze is under way.
 	titling sync.RWMutex
+	// sending serializes SendToChat, so a week is posted to Google Chat
+	// once however many sends race.
+	sending sync.Mutex
 }
 
 // NewService returns a service over st that titles Supply runs with title
-// in KindTitleSupplyRun jobs, which it registers on runner, and logs to
-// logger. runner must not have started yet.
-func NewService(st *store.Store, title Titler, runner *jobs.Runner, logger *slog.Logger) (*Service, error) {
+// in KindTitleSupplyRun jobs, which it registers on runner, tells the
+// household through notifier, which must be over st, sends Supply runs to
+// Google Chat through chatSvc, and logs to logger. runner must not have
+// started yet.
+func NewService(st *store.Store, title Titler, runner *jobs.Runner, notifier *notify.Service, chatSvc *chat.Service, logger *slog.Logger) (*Service, error) {
 	switch {
 	case st == nil:
 		return nil, errors.New("shopping: nil store")
@@ -117,10 +126,14 @@ func NewService(st *store.Store, title Titler, runner *jobs.Runner, logger *slog
 		return nil, errors.New("shopping: nil titler")
 	case runner == nil:
 		return nil, errors.New("shopping: nil job runner")
+	case notifier == nil:
+		return nil, errors.New("shopping: nil notifier")
+	case chatSvc == nil:
+		return nil, errors.New("shopping: nil chat service")
 	case logger == nil:
 		return nil, errors.New("shopping: nil logger")
 	}
-	s := &Service{st: st, title: title, logger: logger, now: time.Now}
+	s := &Service{st: st, title: title, notifier: notifier, chat: chatSvc, logger: logger, now: time.Now}
 	kind, err := jobs.Register(runner, KindTitleSupplyRun, s.runTitleJob, ReasonTitleFailed)
 	if err != nil {
 		return nil, err
@@ -272,6 +285,7 @@ func (s *Service) generate(ctx context.Context, weekStart store.LocalDate, check
 		return Generated{}, fmt.Errorf("shopping: generate: %w", err)
 	}
 	var out Generated
+	notified := false
 	err := s.st.WithTx(ctx, func(tx *sql.Tx) error {
 		q := db.New(tx)
 		plan, err := q.GetWeekPlan(ctx, weekStart.String())
@@ -293,8 +307,9 @@ func (s *Service) generate(ctx context.Context, weekStart store.LocalDate, check
 		if err != nil && !errors.Is(err, sql.ErrNoRows) {
 			return fmt.Errorf("shopping: read list: %w", err)
 		}
+		created := err != nil
 		switch {
-		case err != nil: // no list yet
+		case created: // no list yet
 			list = db.ShoppingList{ID: store.NewID(), WeekStart: weekStart.String(), PlanID: plan.ID, Status: StatusCurrent}
 			err = q.CreateShoppingList(ctx, db.CreateShoppingListParams{
 				ID: list.ID, WeekStart: list.WeekStart, PlanID: list.PlanID, CreatedAt: now, UpdatedAt: now,
@@ -313,6 +328,13 @@ func (s *Service) generate(ctx context.Context, weekStart store.LocalDate, check
 			return err
 		}
 		out = Generated{List: listOf(list, groups), Skipped: skipped}
+		if created {
+			ev := chat.ListReady(weekStart, out.List.Counts().Needed, len(groups))
+			if err := s.notifier.EmitTx(ctx, tx, ev); err != nil {
+				return fmt.Errorf("shopping: %w", err)
+			}
+			notified = true
+		}
 		if list.Title.Valid {
 			return nil
 		}
@@ -331,6 +353,9 @@ func (s *Service) generate(ctx context.Context, weekStart store.LocalDate, check
 	if out.TitleJobID != nil {
 		s.titleJob.Wake()
 	}
+	if notified {
+		s.notifier.Wake()
+	}
 	return out, nil
 }