feat: add i18n descriptions to all hands and channels (#22)

Add [i18n.zh], [i18n.zh-TW], [i18n.ja], [i18n.ko], [i18n.de], [i18n.es]
sections with translated descriptions to:
- 15 Hand TOML files (hands/*/HAND.toml)
- 44 Channel TOML files (channels/*.toml)

This enables the website to display localized Hand and Channel descriptions
based on the user's selected language.

channels/webhook.toml

@@ -5,6 +5,24 @@ category = "developer"
 icon = "🔗"
 protocol = "webhook"
 
+[i18n.zh]
+description = "通用 Webhook 适配器，通过 HTTP 回调收发消息"
+
+[i18n.zh-TW]
+description = "通用 Webhook 適配器，透過 HTTP 回呼收發訊息"
+
+[i18n.ja]
+description = "汎用Webhookアダプター、HTTPコールバックによるメッセージの送受信"
+
+[i18n.ko]
+description = "범용 Webhook 어댑터, HTTP 콜백을 통한 메시지 송수신"
+
+[i18n.de]
+description = "Generischer Webhook-Adapter zum Senden und Empfangen von Nachrichten über HTTP-Callbacks"
+
+[i18n.es]
+description = "Adaptador de webhook genérico para enviar y recibir mensajes mediante callbacks HTTP"
+
 [metadata]
 url = ""
 docs = ""