[PoC DO NOT MERGE] hfjobs uv run

[davanstrien]

⚠️ This is a Proof of Concept PR - NOT intended for merge yet. Seeking feedback on the UX.

Most of the code was written by Claude via Claude Code. If we decide to add this feature, I will probably open a new clean PR to better align with the rest of the hfjobs code.

This PR introduces a new hfjobs uv command suite focused on making it easier to run UV scripts on HF infrastructure.

New subcommands:

• hfjobs uv init - Create a HF dataset repository for UV scripts
• hfjobs uv push - Push scripts to an existing repository
• hfjobs uv sync - Sync local scripts to repository
• hfjobs uv run - Run a UV script directly on HF infrastructure (main feature)

Key feature: hfjobs uv run

The highlight is the ability to run local UV scripts with a single command:

# Run a local UV script immediately
hfjobs uv run my_script.py

# With arguments
hfjobs uv run my_script.py arg1 arg2 --option value

# With specific hardware
hfjobs uv run my_script.py --flavor gpu-a10g-small

# Using a persistent repository for multiple runs
hfjobs uv run my_script.py --repo my-scripts

How it works:

1. Automatically uploads the script to a HF dataset repository
2. Executes using the official UV Docker container
3. Streams output back to the terminal

Repository management:

- Ephemeral repos: Auto-created for one-off runs (username/hfjobs-uv-run-TIMESTAMP-HASH)
- Persistent repos: Specified with --repo for organizing script collections

Questions for feedback:

1. Is the UX intuitive? Any suggestions for the command structure?
2. Should we add a --from-repo option to run scripts directly from shared repos?
3. Any concerns about the ephemeral repository approach?

It could make things simpler to enforce a single script per repo, but for related scripts, it might be nicer to have them in the same repo. 

One feature that could be quite cool is to have a 

```bash
hfjobs uv run --from-repo davanstrien/my-cool-script --args 1 --arg2 

This would require a bit of thought about how to manage a default image / suggested hardware etc. It could be possible to do via a config file(s) in the repo but I'm not sure what the best approach for this would be. I would suggest that this is something to only explore once we've seen some in the wild usage anyway to see how people are using and sharing scripts/ hfjobs.

Try it out:

 uv pip install git+https://github.com/davanstrien/hfjobs.git@feat/uv-run-command