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/line.toml

@@ -5,6 +5,24 @@ category = "messaging"
 icon = "🟢"
 protocol = "webhook"
 
+[i18n.zh]
+description = "LINE Messaging API 适配器，在 LINE 平台上收发消息"
+
+[i18n.zh-TW]
+description = "LINE Messaging API 適配器，在 LINE 平台上收發訊息"
+
+[i18n.ja]
+description = "LINE Messaging APIアダプター、LINEプラットフォームでのメッセージ送受信"
+
+[i18n.ko]
+description = "LINE Messaging API 어댑터, LINE 플랫폼에서 메시지 송수신"
+
+[i18n.de]
+description = "LINE Messaging API-Adapter zum Senden und Empfangen von Nachrichten auf der LINE-Plattform"
+
+[i18n.es]
+description = "Adaptador de LINE Messaging API para enviar y recibir mensajes en la plataforma LINE"
+
 [metadata]
 url = "https://line.me"
 docs = "https://developers.line.biz/en/docs/messaging-api/"