Remove standalone install note

Standalone live_infer.py (no livediffusion package)

Update EMA weights to checkpoint step 700

Document download + run commands; ship live_infer.py

Drop 'That's the whole demo.'

Trim model card; example uses 2 steps

Diffusion Pong EMA step 650, demo gif, model card

Diffusion Pong EMA step 650 + live play card

initial commit