fix(transform): remove developer note from user-facing error message

[luanamatiello12-cloud]

Fix the error message in unsupportedParts() that included "Inform the user." — a developer note that was accidentally left in the user-facing error output.

Before:

ERROR: Cannot read "image.png" (this model does not support image input). Inform the user.

After:

ERROR: Cannot read "image.png" (this model does not support image input).

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[github-actions]

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