feat: support Qwen Image 2.1 local generation and editing

[atomantic]

Summary

Add Qwen-Image 2.1 to the local Image Gen catalog and Hugging Face import flow using its new QwenImage21Pipeline. Existing registries receive the choice without replacing customized legacy entries.

The renderer supports text-to-image and single-init-image editing, preserves RGBA inputs/output, passes the supported guidance parameter, and applies the new latent scaling to previews. Both runtime installers now install Transformers >=5.17 and verify the new pipeline. Documentation covers setup, the research license, and the current single-reference scope.

Upstream contract: https://github.com/QwenLM/Qwen-Image-2.1 and huggingface/diffusers#14804.

Test plan

• 262 focused JavaScript tests passed across registry, Hugging Face import, Python setup, local dispatch, and shell setup suites.
• python3 scripts/z_image_turbo_test.py: generation/editing fixture passed, including alpha preservation and native edit dispatch.
• bash -n scripts/setup-image-video.sh and git diff --check passed.
• npm run pregate: passed client lint and 219 selected server tests/guards.
• Full-weight inference and hardware memory requirements are not validated; no model weights downloaded. Multi-reference/mask editing is not exposed by this change.

[atomantic]

Required CI is blocked by the shared server import-budget failure: 116,547 static module instantiations versus the 116,500 cap. The first failing job is https://github.com/atomantic/PortOS/actions/runs/35530318769/job/106129674884; fail-fast canceled the remaining jobs. The same failure reproduces locally, and #7807 independently reports the identical baseline count on origin/main.

Tracked in #7810. A bounded lazy-import experiment in the image setup module saved only seven instantiations and was reverted; the PR's image-generation implementation remains unchanged at ac06aad. Focused tests and pregate passed as documented in the PR. This PR is left OPEN, not merged over red CI. Repair the baseline under #7810, synchronize this branch, rerun the required local review if rebasing, and require the complete CI rollup before merging.