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/messages_test.go

@@ -36,7 +36,7 @@ func TestMessages(t *testing.T) {
 	}{
 		{
 			name:  "plan ready",
-			ev:    PlanReady(week, []string{"Tacos", "Bolognese", "Tikka masala", "Lemon orzo", "Bibimbap", "Shakshuka", "Chili"}),
+			ev:    PlanReady(week, week, []string{"Tacos", "Bolognese", "Tikka masala", "Lemon orzo", "Bibimbap", "Shakshuka", "Chili"}),
 			key:   "plan_ready:2026-10-12",
 			url:   "/plan",
 			week:  "2026-10-12",
@@ -46,7 +46,7 @@ func TestMessages(t *testing.T) {
 		},
 		{
 			name:  "plan ready with three dinners",
-			ev:    PlanReady(week, []string{"Tacos", "Bolognese", "Tikka masala"}),
+			ev:    PlanReady(week, week, []string{"Tacos", "Bolognese", "Tikka masala"}),
 			key:   "plan_ready:2026-10-12",
 			url:   "/plan",
 			week:  "2026-10-12",
@@ -54,6 +54,26 @@ func TestMessages(t *testing.T) {
 			body:  "Tacos, Bolognese, Tikka masala",
 			chatT: "This week's plan is ready: Tacos, Bolognese, Tikka masala. Open the plan →",
 		},
+		{
+			name:  "plan ready for next week",
+			ev:    PlanReady(week, mustDate(t, "2026-10-05"), []string{"Tacos", "Bolognese", "Tikka masala", "Lemon orzo"}),
+			key:   "plan_ready:2026-10-12",
+			url:   "/plan",
+			week:  "2026-10-12",
+			title: "Next week's plan is ready",
+			body:  "Tacos, Bolognese, Tikka masala + 1 more",
+			chatT: "Next week's plan is ready: Tacos, Bolognese, Tikka masala + 1 more. Open the plan →",
+		},
+		{
+			name:  "plan ready for a later week",
+			ev:    PlanReady(mustDate(t, "2026-10-26"), mustDate(t, "2026-10-05"), []string{"Tacos"}),
+			key:   "plan_ready:2026-10-26",
+			url:   "/plan",
+			week:  "2026-10-26",
+			title: "The plan for the week of Oct 26 is ready",
+			body:  "Tacos",
+			chatT: "The plan for the week of Oct 26 is ready: Tacos. Open the plan →",
+		},
 		{
 			name:  "list ready",
 			ev:    ListReady(week, 19, 7),
@@ -115,6 +135,23 @@ func TestMessages(t *testing.T) {
 	}
 }
 
+func TestSupplyRunText(t *testing.T) {
+	t.Parallel()
+	got := SupplyRunText("Week 42 · Oct 12 – 18", []SupplyRunGroup{
+		{Dinner: "Tacos", Items: []SupplyRunItem{{Name: "ground beef", Qty: "1 lb"}, {Name: "tortillas"}}},
+		{Dinner: "Bolognese"},
+		{Dinner: "Pho", Items: []SupplyRunItem{{Name: "rice noodles", Qty: "200 g"}}},
+	})
+	want := "Supply run · Week 42 · Oct 12 – 18\n\n*Tacos*\n• ground beef — 1 lb\n• tortillas\n\n*Pho*\n• rice noodles — 200 g\n\nOpen the Supply run →"
+	if got != want {
+		t.Errorf("SupplyRunText =\n%s\nwant\n%s", got, want)
+	}
+	got = SupplyRunText("Cozy week", []SupplyRunGroup{{Dinner: "Tacos"}})
+	if want := "Supply run · Cozy week\n\nNothing left to buy.\n\nOpen the Supply run →"; got != want {
+		t.Errorf("SupplyRunText with nothing needed = %q, want %q", got, want)
+	}
+}
+
 func TestTextWithoutBody(t *testing.T) {
 	t.Parallel()
 	got := Text(notify.Payload{Event: notify.PlanReady, Title: "This week's plan is ready", URL: "/plan"})