Fix Home dashboard integration findings (Feature 21)

- F21-01: plan_ready and list_ready links carry their week
  (/plan?week=, /plan/shopping?week=), and the Plan opens on ?week=
  and keeps it on the week shown, so an older update opens its week.
- F21-02: a failed refresh of the Rotation check shows its ErrorBanner
  beside the cached pending card instead of replacing it.
- F21-03: Home carries the household's timezone and is read again at
  its next local midnight.
- F21-04: Home counts pending Side quests through a read-only query
  (suggest.PendingCount), so reading Home never writes batches.

Task: ac3dddf0-a05f-4e43-a5ad-3105fe6bdd95

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

internal/shopping/notify_test.go

@@ -37,9 +37,9 @@ func TestGenerateEmitsListReadyOnce(t *testing.T) {
 	}
 	for _, r := range rows {
 		p := r.Payload
-		if r.Key != "list_ready:2026-10-12" || p.URL != "/plan/shopping" || p.Week != "2026-10-12" ||
+		if r.Key != "list_ready:2026-10-12" || p.URL != "/plan/shopping?week=2026-10-12" || p.Week != "2026-10-12" ||
 			p.Title != "This week's Supply run is ready" || p.Body != "3 items to buy for 2 dinners" {
-			t.Errorf("%s row = %+v, want list_ready:2026-10-12, 3 items for 2 dinners, /plan/shopping", r.Channel, r)
+			t.Errorf("%s row = %+v, want list_ready:2026-10-12, 3 items for 2 dinners, /plan/shopping?week=2026-10-12", r.Channel, r)
 		}
 	}