fix(diffusion): inherit cpu offload hooks in from_pipe pipelines

[ChristianGruend]

Summary

from_pipe() does not carry over CPU offload hooks from the source pipeline. When --cpu-offload is enabled, inpaint and img2img pipelines created via from_pipe() load their shared components fully onto the GPU instead of respecting the offload setting, causing an out-of-memory crash.

Target branch

• This PR targets dev.

Linked Issue

Fixes #5759 — no separate issue was opened; the bug was discovered and fixed directly while testing CPU offload with inpaint/img2img pipelines.

Type of Change

• Bug fix (non-breaking — fixes a confirmed issue)

Checklist

• I searched open issues and open PRs — this is not a duplicate.
• My changes are limited to the scope described above — no unrelated refactors or whitespace changes mixed in.
• I actually ran the app (docker compose up) and verified the change works end-to-end.

How to Test

1. Start the app with --cpu-offload enabled.
2. Load an image and trigger the inpaint or img2img pipeline (this uses from_pipe() internally to share the base pipeline).
3. Without the fix: the process OOMs because the shared components load fully onto the GPU. With the fix: enable_model_cpu_offload() is called explicitly and the pipeline runs without OOM.

Visual / UI changes

Not applicable — this is a backend-only fix in scripts/diffusion_server.py, no UI/rendering code touched.