Televiz Quick Start snippet imports `cupy`, which is never listed as a prerequisite

Found during internal QA of the 1.4 release.

The Televiz Quick Start tells you to install with pip install isaacteleop, and then the first runnable snippet on the same page opens with import cupy as cp. cupy is not a dependency of the wheel and is never listed as a prerequisite, so the snippet fails on a clean environment with ModuleNotFoundError: No module named 'cupy'. It runs once cupy is installed by hand.

Where

• Install step — docs/source/getting_started/televiz.rst L32: pip install isaacteleop
• Snippet — docs/source/getting_started/televiz.rst L103: import cupy as cp
• Published page: https://nvidia.github.io/IsaacTeleop/release/1.4.x/getting_started/televiz.html

Why it fails

cupy appears in no dependency list in pyproject.toml — not in [project] dependencies (numpy, pyyaml) and not in any extra (dev, ui, retargeters, retargeters-lite, grounding, cloudxr). Verified identical on main and release/1.4.x.

Suggested fix

Either list cupy as a prerequisite ahead of the snippet — with the CUDA-matched package name, e.g. cupy-cuda12x, since a bare pip install cupy is not what most people want — or rewrite the snippet against a VizBuffer / NumPy path so the Quick Start runs on a bare pip install isaacteleop. The page already notes that any __cuda_array_interface__ producer works (CuPy / PyTorch / Numba), so CuPy is illustrative here rather than required, which argues for the second option.