fix(app): FLUX on Windows hard crash

[psychedelicious]

Summary

A recent update to sentencepiece causes a hard crash in Windows. The crash occurs when transformers attempts to load the vocab via sentencepiece: https://github.com/huggingface/transformers/blame/b824f4986f9c13faffac1df016ae663e00adc755/src/transformers/models/t5/tokenization_t5.py#L150

I will try to create a minimal repro for sentencepiece later.

Related Issues / Discussions

Closes #8486

QA Instructions

You can test this on Windows by manually downloading sentencepiece. Open the Launcher's Dev Console and run:

uv pip install sentencepiece==0.2.0

Then start Invoke and generate with FLUX.

I also tested by building the wheel based on this branch in CI (this run) and installing it via Dev Console like this:

uv pip install ..\Downloads\invokeai-6.5.0-py3-none-any.whl --force-reinstall --extra-index-url https://download.pyt
orch.org/whl/cu128

Merge Plan

Will do a patch release.

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)

[psychedelicious]

Also bumps version