fix(model_manager): prevent Z-Image LoRAs from being misclassified as main models

[Pfannkuchensack]

Summary

Z-Image LoRAs containing keys like diffusion_model.context_refiner.* were being incorrectly classified as main checkpoint models instead of LoRAs. This happened because the _has_z_image_keys() function checked for Z-Image specific keys (like context_refiner) without verifying if the file was actually a LoRA.

Since main models have higher priority than LoRAs in the classification sort order, the incorrect main model classification would win.

The fix adds detection of LoRA-specific weight suffixes (.lora_down.weight, .lora_up.weight, .lora_A.weight, .lora_B.weight, .dora_scale) and returns False if any are found, ensuring LoRAs are correctly classified.

Related Issues / Discussions

#8707

QA Instructions

1. Import a Z-Image LoRA file (e.g., one with diffusion_model.context_refiner.* or diffusion_model.layers.* keys)
2. Verify it is classified as LoRA type with z-image base and lycoris format
3. Import a Z-Image main model checkpoint
4. Verify it is still correctly classified as Main type with z-image base

Merge Plan

Standard merge, no special considerations.

Checklist

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

[JPPhoto]

Does this reclassify existing models if somebody reidentifies?

[Pfannkuchensack]

This will fix any Lora that got identifies as Model right if reidentifies again.

[lstein]

Looks good to me.

[JPPhoto]

Sorry, I wasn't clear. I think you should remove has_z_image_keys and should return True if found, else return False. That variable didn't add much since there's no block below that in the code that depends on its value.