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/email.toml

@@ -5,6 +5,24 @@ category = "email"
 icon = "📧"
 protocol = "imap"
 
+[i18n.zh]
+description = "电子邮件适配器，通过 SMTP 和 IMAP 协议收发邮件"
+
+[i18n.zh-TW]
+description = "電子郵件適配器，透過 SMTP 和 IMAP 協議收發郵件"
+
+[i18n.ja]
+description = "メールアダプター、SMTPとIMAPプロトコルによるメッセージの送受信"
+
+[i18n.ko]
+description = "이메일 어댑터, SMTP 및 IMAP 프로토콜을 통한 메시지 송수신"
+
+[i18n.de]
+description = "E-Mail-Adapter zum Senden und Empfangen von Nachrichten über SMTP- und IMAP-Protokolle"
+
+[i18n.es]
+description = "Adaptador de correo electrónico para enviar y recibir mensajes mediante protocolos SMTP e IMAP"
+
 [metadata]
 url = ""
 docs = ""