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/chat/chat_test.go

@@ -304,7 +304,7 @@ func TestSendThreadsByWeek(t *testing.T) {
 	}
 	week := mustDate(t, "2026-10-12")
 	events := []notify.Event{
-		PlanReady(week, []string{"Tacos", "Bolognese", "Tikka masala", "A", "B", "C", "D"}),
+		PlanReady(week, week, []string{"Tacos", "Bolognese", "Tikka masala", "A", "B", "C", "D"}),
 		ListReady(week, 19, 7),
 		DayOfReminder(mustDate(t, "2026-10-18"), "01J9DINNER", "Tacos"),
 		NewSuggestions("01J9BATCH", week, []string{"Pho"}),
@@ -383,7 +383,7 @@ func TestSendClassifiesStatus(t *testing.T) {
 	if _, err := svc.Put(ctx, testHook, "Family"); err != nil {
 		t.Fatal(err)
 	}
-	m := notify.Message{Payload: payloadOf(PlanReady(mustDate(t, "2026-10-12"), []string{"Tacos"}))}
+	m := notify.Message{Payload: payloadOf(PlanReady(mustDate(t, "2026-10-12"), mustDate(t, "2026-10-12"), []string{"Tacos"}))}
 	for _, tc := range []struct {
 		status        int
 		ok, permanent bool
@@ -464,7 +464,7 @@ func TestOutboxRowsFollowClassification(t *testing.T) {
 
 	week := mustDate(t, "2026-10-12")
 	f.setStatus(http.StatusBadRequest)
-	planned := PlanReady(week, []string{"Tacos"})
+	planned := PlanReady(week, week, []string{"Tacos"})
 	if err := notifier.Emit(ctx, planned); err != nil {
 		t.Fatal(err)
 	}
@@ -528,3 +528,61 @@ func (b *syncBuffer) String() string {
 	defer b.mu.Unlock()
 	return b.buf.String()
 }
+
+func TestPostSupplyRun(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	f := newFakeChat(t)
+	svc, _ := newTestService(t, f)
+	week := mustDate(t, "2026-10-12")
+	groups := []SupplyRunGroup{{Dinner: "Tacos", Items: []SupplyRunItem{{Name: "tortillas"}}}}
+
+	if err := svc.PostSupplyRun(ctx, week, "Week 42 · Oct 12 – 18", groups); !errors.Is(err, ErrNotConfigured) {
+		t.Fatalf("PostSupplyRun without a webhook = %v, want ErrNotConfigured", err)
+	}
+	if _, err := svc.Put(ctx, testHook, "Family"); err != nil {
+		t.Fatal(err)
+	}
+	if err := svc.PostSupplyRun(ctx, week, "Week 42 · Oct 12 – 18", groups); err != nil {
+		t.Fatal(err)
+	}
+	reqs := f.requests()
+	if len(reqs) != 1 {
+		t.Fatalf("Chat got %d requests, want 1", len(reqs))
+	}
+	r := reqs[0]
+	if r.Query.Get("threadKey") != "mealquest-week-2026-W42" || r.Query.Get("messageReplyOption") != replyOption {
+		t.Errorf("threading = %v", r.Query)
+	}
+	if want := SupplyRunText("Week 42 · Oct 12 – 18", groups); r.Body["text"] != want {
+		t.Errorf("text = %q, want %q", r.Body["text"], want)
+	}
+	data, _ := json.Marshal(r.Body["cardsV2"])
+	var cards []cardV2
+	if err := json.Unmarshal(data, &cards); err != nil || len(cards) != 1 {
+		t.Fatalf("cardsV2 = %s, %v", data, err)
+	}
+	buttons := cards[0].Card.Sections[0].Widgets[0].ButtonList.Buttons
+	if cards[0].Card.Header.Title != "Supply run · Week 42 · Oct 12 – 18" || len(buttons) != 1 ||
+		buttons[0].OnClick.OpenLink.URL != "https://mealquest.example/plan/shopping?week=2026-10-12" {
+		t.Errorf("card = %s, want an Open button to the week's Supply run", data)
+	}
+
+	f.setStatus(http.StatusForbidden)
+	err := svc.PostSupplyRun(ctx, week, "Week 42 · Oct 12 – 18", groups)
+	if !errors.Is(err, ErrRefused) || !strings.Contains(err.Error(), "403") {
+		t.Errorf("PostSupplyRun answered 403 = %v, want ErrRefused with the status", err)
+	}
+	if err != nil {
+		assertNoSecret(t, "refused error", err.Error())
+	}
+
+	f.srv.Close()
+	err = svc.PostSupplyRun(ctx, week, "Week 42 · Oct 12 – 18", groups)
+	if !errors.Is(err, ErrUnreachable) {
+		t.Errorf("PostSupplyRun unanswered = %v, want ErrUnreachable", err)
+	}
+	if err != nil {
+		assertNoSecret(t, "unreachable error", err.Error())
+	}
+}