docs: Enable docs self-publishing including nightly update

[chtruong814]

What does this PR do ?

docs: Enable docs self-publishing including nightly update

• Added initial uv.lock file. This is not used for any CI right now. Only for docs build but we will eventualy adapt Speech repo to use uv.
• Fixed some docs issues during the build including resolving some docstring errors. Not sure why this wasn't being caught earlier
• Updated main title to say NeMo Speech

Example dry run:
https://github.com/NVIDIA-NeMo/NeMo/actions/runs/22370634701

Published nightly docs:
https://docs.nvidia.com/nemo/speech/nightly/index.html

Collection: [Note which collection this PR will affect]

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[pzelasko]

Looks good to me, but do we need uv.lock file to be present in the repo?