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/chat/messages.go

@@ -2,6 +2,7 @@ package chat
 
 import (
 	"fmt"
+	"net/url"
 	"strings"
 	"time"
 
@@ -46,7 +47,7 @@ func PlanReady(week, thisWeek store.LocalDate, dinners []string) notify.Event {
 		Key:   string(notify.PlanReady) + ":" + week.String(),
 		Title: planTitle(week, thisWeek),
 		Body:  nameList(dinners),
-		URL:   "/plan",
+		URL:   "/plan?" + url.Values{"week": {week.String()}}.Encode(),
 		Week:  week,
 	}
 }
@@ -59,7 +60,7 @@ func ListReady(week store.LocalDate, needed, dinners int) notify.Event {
 		Key:   string(notify.ListReady) + ":" + week.String(),
 		Title: "This week's Supply run is ready",
 		Body:  fmt.Sprintf("%s to buy for %s", count(needed, "item", "items"), count(dinners, "dinner", "dinners")),
-		URL:   "/plan/shopping",
+		URL:   "/plan/shopping?" + url.Values{"week": {week.String()}}.Encode(),
 		Week:  week,
 	}
 }