ui: show log line numbers + allow deep links

# Summary

I think it can be awesome if the UI would have line numbers for each output log line and allow deep linking into a specific line.

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> (photo taken from Github Action but almost every common workflow / CI engine has this feature)

# Use Cases

- Looking at a very long log output may be hard.
- Sometimes you want to share a link to a specific line in the output showing the problem.

**Message from the maintainers**:

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The issue names the UI workflow-log output as the entry point but provides no files or tests. Locate the component that renders workflow logs and investigate how a selected line could be represented in a shareable link; done means each output line has a visible number and links open the corresponding line.

Written by the indexing model from the issue text.