fix(ui): Fix translation reference in models picker

[hipsterusername]

Summary

The fix replaces the incorrect t('models.selectModelFirst') with the correct and existing t('models.selectModel') in invokeai/frontend/web/src/features/lora/components/LoRASelect.tsx.

Related Issues / Discussions

N/A

QA Instructions

1. Navigate to the LoRA/Concepts section in the UI.
2. Ensure that no base model is currently selected.
3. Verify that the LoRA select dropdown displays "Select a Model" (or its translated equivalent) as its placeholder text.
4. Open the LoRA select dropdown and confirm that the "no options" text also displays "Select a Model" (or its translated equivalent).
5. Enjoy the fix. Luxuriate in the translation.

Merge Plan

N/A

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)