phsl / new-api

• Unify the Select option structure as `{ key, label, value }`; add missing `key` to prevent duplicated rendering by Semi-UI.
• Trim and deduplicate the `models` array via `Set` inside `handleInputChange`, ensuring state always contains unique values.
• In the options-merging `useEffect`, use a `Map` keyed by `value` (after `trim`) to guarantee a unique `optionList` when combining backend data with currently selected models.
• Apply the same structure and de-duplication when:
  – Fetching models from `/api/channel/models`
  – Adding custom models (`addCustomModels`)
  – Fetching upstream model lists (`fetchUpstreamModelList`)
• Replace obsolete `text` field with `label` in custom option objects for consistency.

No backend changes are required; the fix is entirely front-end.

Closes #1292