feat: enable circular RoPE for qwen2.1

[stduhpf]

Summary

Improve support for --circular, --circularx, and --circulary flags with Qwen-Image 2.1.

Related Issue / Discussion

#914

Additional Information

sd-cli.exe --diffusion-model models\qwen_image_2.1-Q8_0.gguf --llm 'models\Qwen\Qwen3-VL-8B-Instruct-Q4_K_M.gguf' --llm_vision 'models\Qwen\mmproj-Qwen3VL-8B-Instruct-Q8_0.gguf' --vae models\vae\wan-qwen\qwen_image_2.1_vae_bf16.safetensors --cfg-scale 3.5 --steps 20 --seed 42 --vae-conv-direct --prompt-file prompt-file.txt -r assets\cat_with_sd_cpp_42.png -W 1024 -H 512 --diffusion-fa --extra-sample-args guidance_schedule=1x7

prompt-file.txt:

将这张图片转换为完整的 360°沉浸式全景图，采用标准 Equirectangular 等距柱状投影，2:1画幅。

保持原图中的人物、场景、物体、服装、材质、色彩、光影和整体视觉风格不变。

将原本有限的视野扩展为完整的 360°水平环绕视角 + 180°垂直视角，补全原图视野之外的环境，使前后左右以及上下空间自然连续。

画面必须具有完整的空间连续性，避免重复物体、断裂结构、拼接痕迹、明显变形和透视错误。

确保全景图首尾能够无缝连接，左右边缘内容自然衔接，地面、墙壁、建筑、人物和环境结构保持连续。

输出为真实完整的360°VR全景图，Equirectangular Projection，2:1，seamless 360 panorama，immersive panoramic environment，consistent lighting and geometry。）

Without --circularx, visible seam as expected

Master branch, with --circularx, lots of artifacts around the seam, even more visible

PR, with --circularx, seamless

Note that the overall quality of the generation is slightly degraded, the room no longer has 4 nice straight walls when cirular tiling is enabled, but artifacts and seams are gone.

Checklist

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

[leejet]

Thanks for your contribution! This has been superseded by #2039.

Having to modify RoPE every time to accommodate the circular logic was getting pretty cumbersome, so I abstracted it into a generic post-processing step instead. This should make integrating new models much easier.