Add Daily Digest notification preferences with custom time support

- Add daily_digest boolean and daily_digest_hour fields to NotificationPreference model
- Update HandleDailyDigest to check user preferences and custom notification times
- Change Daily Digest scheduler to run hourly (supports per-user custom times)
- Update notification service DTOs for new fields
- Add Daily Digest toggle and custom time to admin notification prefs page
- Fix notification handlers to only notify users at their designated hour

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

cmd/worker/main.go

@@ -117,12 +117,12 @@ func main() {
 	}
 	log.Info().Str("cron", "0 * * * *").Int("default_hour", cfg.Worker.OverdueReminderHour).Msg("Registered overdue reminder job (runs hourly for per-user times)")
 
-	// Schedule daily digest (runs at configured hour - no per-user customization yet)
-	dailyCron := formatCron(cfg.Worker.DailyNotifHour)
-	if _, err := scheduler.Register(dailyCron, asynq.NewTask(jobs.TypeDailyDigest, nil)); err != nil {
+	// Schedule daily digest (runs every hour to support per-user custom times)
+	// The job handler filters users based on their preferred notification hour
+	if _, err := scheduler.Register("0 * * * *", asynq.NewTask(jobs.TypeDailyDigest, nil)); err != nil {
 		log.Fatal().Err(err).Msg("Failed to register daily digest job")
 	}
-	log.Info().Str("cron", dailyCron).Msg("Registered daily digest job")
+	log.Info().Str("cron", "0 * * * *").Int("default_hour", cfg.Worker.DailyNotifHour).Msg("Registered daily digest job (runs hourly for per-user times)")
 
 	// Handle graceful shutdown
 	quit := make(chan os.Signal, 1)