skills

Remove broken Security.md link for cuPyNumeric

chore: sync skills (Model-Optimizer,NeMo Gym,NeMo Platform,NeMo Retriever,NeMo-Gym,Nemotron Voice Agent,Physical AI,TensorRT-LLM,TileGym,Video Search and Summarization,nemotron-voice-agent,tilegym-converting-cutile-to-julia,tilegym-converting-cutile-to-triton,tilegym-cutile-autotuning,tilegym-cutile-python,tilegym-improve-cutile-kernel-perf,tilegym-monkey-patch-kernels-to-transformers)

chore(physical-ai): update product description to broader scope

chore(readme): replace Source + Version columns with per-skill links

docs(readme,contributing): point at new catalog issue templates