RTX 5090 compatibility guards for CompVis LDM variants

[PiercingXX]

Summary

This PR adds defensive compatibility guards so webui can run on modern RTX 5090 + torch nightly stacks when the underlying implementation differs from expected attributes/modules.

Changes

• Guard access in
• Guard access in
• Make import/usage optional in
• Add fallback no-op when is unavailable in
• Make MiDaS import optional and skip autodownload wrapper when unavailable in
• Update default stable diffusion repo/commit in to a reachable CompVis source
• Added detailed docs in

Validation

• Confirmed torch/cuda runtime sees
• Confirmed webui startup path reaches with smoke flags
• Confirmed HTTP endpoint returns web UI HTML

Notes

• Full image generation still requires checkpoint presence/download in runtime environment.