Seed household settings at boot and serve the settings API

On first boot create the single household_settings row with the zone from
MEALQUEST_DEFAULT_TZ and the seed times and days (dinner 17:30, reminder
16:30, rotation check 09:00, plan draft Fri 09:00, suggestions Sun 08:00,
chat autosend Sat 08:00). Boot fails if the row is missing and the zone is
unset; an existing row is never overwritten. Config validates the zone
whenever it is set.

Add household.SettingsService with Get, a validating Update (IANA zone,
zero-padded 24-hour HH:MM, day of week 0-6) that records updated_by, and
in-process Subscribe for the scheduler. Serve it as GET and PATCH
/api/v1/settings/household; invalid input is a 400 in the standard error
body. Migration 0002 adds household_settings.updated_by, and
internal/actor carries the member name in the request context.

Link time/tzdata from internal/household so zones load in the minimal
image, which has no system zone database.

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

cmd/server/main.go

@@ -15,6 +15,7 @@ import (
 
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/config"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/frontend"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/server"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
@@ -56,7 +57,12 @@ func run(cfg config.Config, logger *slog.Logger) error {
 		}
 	}()
 
-	router, err := server.NewRouter(logger, version, frontend.Assets())
+	if err := seedSettings(ctx, db, cfg.DefaultTZ); err != nil {
+		return err
+	}
+	settings := household.NewSettingsService(db)
+
+	router, err := server.NewRouter(logger, version, frontend.Assets(), settings)
 	if err != nil {
 		return err
 	}
@@ -118,6 +124,16 @@ func openStore(ctx context.Context, dataDir string) (*store.Store, error) {
 	return db, nil
 }
 
+// seedSettings creates the household settings on first boot, naming the
+// variable that supplies the zone when it is missing.
+func seedSettings(ctx context.Context, db *store.Store, defaultTZ string) error {
+	err := household.SeedSettings(ctx, db, defaultTZ)
+	if errors.Is(err, household.ErrNoDefaultZone) {
+		return fmt.Errorf("%s: required on first boot to create the household settings: %w", config.EnvDefaultTZ, err)
+	}
+	return err
+}
+
 // logListening logs the startup line. Only the public URL's origin is logged
 // so no credential-bearing URL component can reach the log.
 func logListening(logger *slog.Logger, cfg config.Config) {