refactor: Override edit models params

[stduhpf]

Summary

• Unifies all the DiT-based edit models configurations under the new EditModeParams struct.
• adds the --ref-image-mode cli argument to override the configuration
• Enables support for https://github.com/lbouaraba/comfyui-krea2edit / https://huggingface.co/conradlocke/krea2-identity-edit (with the --ref-image-mode "preset=krea2_edit" argument)

Related Issue / Discussion

cont: #1775

Additional Information

The --ref-image-mode uses the same csv format as the --extra-xxx-args arguments.

Here are the supported fields:

Key	Allowed Values	Description
preset	flux_kontext, flux2, qwen_layered, qwen, z_image_omni, krea2_ostris_edit, krea2_edit, default	Sets a predefined group of parameters. If unset, the preset is chosen based on the model architectiure to match previous behavior.
use_vlm	true, false	Determines if references are passed to the Vision Language Model encoder (if applicable).
pass_to_dit	true, false	Determines if VAE-encoded references are passed to the DiT.
ref_index_mode	fixed, increase, decrease	Sets the behavior of the reference images RoPE index.
force_timestep_0	true, false	Forces timestep = 0 for the reference image tokens during diffusion (Note: Only supported by Krea2 architecture).
resize_vae_refs	true, false	Enables/disables resizing of VAE references.
vae_refs_max_size	[integer]	Sets the maximum size for VAE references.
cond_refs_resize_mode	longest_side, area, none	Determines how condition references are resized.
cond_refs_max_size	[integer]	Sets the maximum size for condition references.
cond_refs_min_size	[integer]	Sets the minimum size for condition references.
cond_refs_size	[integer]	Shortcut: Sets both cond_refs_min_size and cond_refs_max_size to this same integer.

Checklist

• I have read and confirmed this PR follows the contribution guidelines.

[MrDrMcCoy]

Would you be so kind as to include an update to the docs that covers all this?