Add job runner timeout option

[markuswustenberg]

Otherwise, the underlying queue could have a much smaller timeout, and the runner wouldn't work properly.

Also:

• Remove the done channel, we can just use jobCtx directly.
• Some more doc comments.
• Add logging before job run.
• Add a test for the extension.

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 89.30%. Comparing base (95eb0b8) to head (3bc7f69).

❗ Current head 3bc7f69 differs from pull request most recent head c0f1701. Consider uploading reports for the commit c0f1701 to get more accurate results

Files	Patch %	Lines
jobs/runner.go	83.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #40      +/-   ##
==========================================
- Coverage   89.47%   89.30%   -0.17%     
==========================================
  Files           3        3              
  Lines         342      346       +4     
==========================================
+ Hits          306      309       +3     
- Misses         27       28       +1     
  Partials        9        9              

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