The API-key PasswordInput is a write-only buffer — the saved key never
loads back, so the built-in visibility toggle reveals nothing. When a key
is saved and the buffer is empty, render a red Clear (X) ActionIcon in the
field's rightSection (which suppresses the Mantine eye); while typing a new
key the default eye returns. Applied to all three AI endpoints (Chat,
Embeddings, Voice/STT). Handlers and payload logic unchanged.
Implements docs/backlog/api-key-field-clear-in-place-of-eye.md.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>