Replace Gorush with direct APNs/FCM integration

- Add direct APNs client using sideshow/apns2 for iOS push
- Add direct FCM client using legacy HTTP API for Android push
- Remove Gorush dependency (no external push server needed)
- Update all services/handlers to use new push.Client
- Update config for APNS_PRODUCTION flag

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

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

cmd/worker/main.go

@@ -39,11 +39,16 @@ func main() {
 	sqlDB, _ := db.DB()
 	defer sqlDB.Close()
 
-	// Initialize push client (optional)
-	var gorushClient *push.GorushClient
-	if cfg.Push.GorushURL != "" {
-		gorushClient = push.NewGorushClient(&cfg.Push)
-		log.Info().Str("url", cfg.Push.GorushURL).Msg("Gorush client initialized")
+	// Initialize push client (APNs + FCM)
+	var pushClient *push.Client
+	pushClient, err = push.NewClient(&cfg.Push)
+	if err != nil {
+		log.Warn().Err(err).Msg("Failed to initialize push client - push notifications disabled")
+	} else {
+		log.Info().
+			Bool("ios_enabled", pushClient.IsIOSEnabled()).
+			Bool("android_enabled", pushClient.IsAndroidEnabled()).
+			Msg("Push notification client initialized")
 	}
 
 	// Initialize email service (optional)
@@ -80,7 +85,7 @@ func main() {
 	)
 
 	// Create job handler
-	jobHandler := jobs.NewHandler(db, gorushClient, emailService, cfg)
+	jobHandler := jobs.NewHandler(db, pushClient, emailService, cfg)
 
 	// Create Asynq mux and register handlers
 	mux := asynq.NewServeMux()