Split environment dependencies and implement lazy imports​

[yghstill]

Split default, diffusion, speculative and vlm to lazy imports​.

• Default (LLM)

pip install angelslim

• Speculative

pip install angelslim[speculative]

• Diffusion

pip install angelslim[diffusion]

• VLM

pip install angelslim[vlm]

• ALL

pip install angelslim[all]