chore: remove + skip button in the chat panel

[EtienneLescot]

Summary

The + skip button in the chat panel is no longer needed and should be removed.

Steps to reproduce

1. Open the chat panel in the editor
2. Locate the + skip control (typically near the message input or attached to an assistant message)

Expected

The + skip button should not be present in the chat panel UI.

Actual

The + skip button is still rendered.

Notes

• Please remove the button, its label / i18n key, and any handler / state that only existed for it.
• Run npm run i18n:check after editing the locale files to keep the 13 locales in sync.
• If a replacement (e.g. "stop generation") is needed, file a follow-up — this issue is just the removal.

Environment

• Version: v1.8.0.rc4
• Area: editor / chat panel

[EtienneLescot]

fixed in next release 1.8.0