fix: align attention_mask padding with appended eos token in clvp

[CharlieKerfoot]

Summary

In _pad_extra_bos_eos_tokens at src/transformers/models/clvp/modeling_clvp.py:144, when add_eos_token=True the eos token is appended to the right of input_ids but attention_mask was padded on the left. The mask no longer lines up with the tokens, so the appended eos position gets the wrong mask value and a real token at position 0 is masked out.

Fix

Pad attention_mask on the right (0, 1) instead of the left (1, 0) so the new mask entry corresponds to the appended eos token.

[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: clvp