Telegram Webhookによるボット操作機能を追加（課題の追加・完了・一覧・スヌーズ対応）

cmd/server/main.go

@@ -17,6 +17,10 @@ func main() {
 
 	cfg := config.Load(*configPath)
 
+	if cfg.Notification.TelegramBotToken != "" && cfg.Notification.TelegramWebhookSecret == "" {
+		log.Fatal("telegram_bot_token is set but telegram_webhook_secret is not set — refusing to start with unauthenticated webhook endpoint")
+	}
+
 	log.Printf("Connecting to database (driver: %s)", cfg.Database.Driver)
 	if err := database.Connect(cfg.Database, cfg.Debug); err != nil {
 		log.Fatalf("Failed to connect to database: %v", err)