Add idea actions: add to Quest log and cook tonight (Feature 18)

POST /api/v1/ideas/{jobId}/items/{i}/quest-log adds idea i of a
succeeded ideas job to the Quest log as a dinner grounded in the idea's
own recipe, with origin ingredients or quick, or answers the dinner it
repeats as it is (the Regular dedupe rule), so repeating the call is
idempotent. POST .../cook-tonight does the same, then puts the dinner on
today (household timezone) of this week's plan through plan.Service.Swap;
with no plan for the week it answers 409 no_plan and changes nothing.

Maestro task 54dcd487-1597-4a91-8493-97f3a7635e2d.

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

internal/plan/plan.go

@@ -423,6 +423,40 @@ func (s *Service) Swap(ctx context.Context, weekStart store.LocalDate, date, din
 	return p, nil
 }
 
+// Tonight returns today, the household-local date now in the household's
+// zone, and the Monday starting its week, when that week has a plan: Swap
+// of that week and day sets tonight's dinner. A week with no plan is
+// ErrNotFound; no plan is made for it, since a plan holds all seven days.
+// The week is always today's own, so Swap never writes a different day.
+func (s *Service) Tonight(ctx context.Context) (week, today store.LocalDate, err error) {
+	tx, err := s.st.Reader.BeginTx(ctx, nil)
+	if err != nil {
+		return store.LocalDate{}, store.LocalDate{}, fmt.Errorf("plan: begin read: %w", err)
+	}
+	defer func() {
+		err = errors.Join(err, tx.Rollback())
+	}()
+	q := db.New(tx)
+	settings, err := q.GetHouseholdSettings(ctx)
+	if err != nil {
+		return store.LocalDate{}, store.LocalDate{}, fmt.Errorf("plan: read household settings: %w", err)
+	}
+	zone, err := household.LoadZone(settings.Timezone)
+	if err != nil {
+		return store.LocalDate{}, store.LocalDate{}, fmt.Errorf("plan: household settings: %w", err)
+	}
+	today = household.Today(time.Now(), zone)
+	week = household.WeekStart(today)
+	_, err = q.GetWeekPlan(ctx, week.String())
+	if errors.Is(err, sql.ErrNoRows) {
+		return store.LocalDate{}, store.LocalDate{}, ErrNotFound
+	}
+	if err != nil {
+		return store.LocalDate{}, store.LocalDate{}, fmt.Errorf("plan: read week %s: %w", week, err)
+	}
+	return week, today, nil
+}
+
 // isNew is plan_days.is_new for a dinner with status: 1 for the Quest log.
 func isNew(status string) int64 {
 	if status == dinners.StatusQuestLog {

internal/plan/rotation_test.go

@@ -335,7 +335,7 @@ func TestOnlyKeepPromotesToRegular(t *testing.T) {
 
 	// Each non-test Go file naming the regular status, and how often.
 	uses := map[string]int{
-		"dinners/dinners.go":      5, // the constant (2), listable, CreateRegular's status and origin
+		"dinners/dinners.go":      6, // the constant (2), listable, CreateRegular's status and origin, AddToQuestLog reusing a Regular as it is
 		"plan/plan.go":            1, // plannable
 		"plan/rotation.go":        1, // decisionStatus[DecisionKeep]
 		"suggest/batch.go":        1, // reads which dinners are Regulars to cite