Add model-tree figure to Description

Add cosmos3_model_tree_edge.png model-tree figure

Edge Description: tighten What's-different and Benchmarks bullets

Edge Description: Benchmarks bullet now covers reasoning + generation

Edge Description: drop Input/Output bullet, add Benchmarks highlight

Add model-specific Description summary

Add Diffusers user guide for Cosmos3 Edge (#52)

Cleanup: remove 6 orphaned example_*_output.* assets superseded by edge_*_output.* (#51)

Engines: add vLLM-Omni and vLLM (listed first) alongside PyTorch

Usage: switch reasnor examples to vLLM (#48)

Usage: switch Generation examples to vLLM-Omni (Nano/Super convention) (#46)

Initial release