Front-end enhancements around “Add custom models”:
• EditChannel.js / EditTagModal.js
– Skip models that already exist instead of blocking the action.
– Collect actually inserted items and display:
• Success toast: “Added N models: model1, model2 …”
• Info toast when no new model detected.
– Keeps UX smooth while preserving deduplication logic.
• i18n
– en.json: added keys
• "已新增 {{count}} 个模型：{{list}}"
• "未发现新增模型"
– Fixed a broken JSON string containing smart quotes to maintain valid syntax.
Result:
Users can bulk-paste model names; duplicates are silently ignored and the UI clearly lists what was incrementally appended. All messages are fully internationalised.
Closes #1218
