Add FLUX Redux support

[RyanJDick]

Summary

This PR adds support for the FLUX Redux model (https://huggingface.co/black-forest-labs/FLUX.1-Redux-dev).

Example

Caption: A gnome at the beach holding a banana

Redux image prompt

Result

Usage

• Install the following Starter Models: SigLIP - google/siglip-so400m-patch14-384 and FLUX Redux
• Sample workflow:

Follow-up: Canvas Integration

@psychedelicious I have left integration of FLUX Redux into the Canvas UI for a follow-up PR, because it is a little hairy.

The Redux model differs from the other IP-Adapter models in the following ways:

• Does not support start/end percentage in the same way
• Does not support weight
• Uses a SigLIP image encoder - not one of the existing CLIP models.
• Supports masked image prompting. Masking is not currently supported for the other FLUX IP Adapter models.

Related Issues / Discussions

N/A

QA Instructions

Tests:

• Test installation of SigLIP and FLUX Redux via the Starter Model tab.
• SigLIP and FLUX Redux appear in the model list.
• Run a FLUX Redux workflow without a mask
• Run a FLUX Redux workflow with a mask
• Run a FLUX Redux workflow with multiple Redux image prompts

Merge Plan

No special instructions.

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)

[hipsterusername]

Happy path testing

Good to go!

[psychedelicious]

Looks great. Let's wait until v5.7.2 stable is released, then we'll get this & the workflow library changes merging in.