feat(docs): add vhs gif

[gfanton]

This PR sets up VHS to generate GIFs, ensuring we always have up-to-date GIFs for documentation. I included sample tapes to demonstrate how to proceed.

Contributors' checklist...

• [ ] Added new tests, or not needed, or not feasible
• [ ] Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• [ ] Updated the official documentation or not needed
• [ ] No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• [ ] Added references to related issues and PRs
• [ ] Provided any useful hints for running manual tests
• [ ] Added new benchmarks to generated graphs, if any. More info here.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 48.37%. Comparing base (de2fc45) to head (246cf27). Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2012      +/-   ##
==========================================
+ Coverage   45.62%   48.37%   +2.75%     
==========================================
  Files         445      409      -36     
  Lines       66233    62070    -4163     
==========================================
- Hits        30219    30029     -190     
+ Misses      33521    29539    -3982     
- Partials     2493     2502       +9     

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[gfanton]

Could you check if nbedos/termtosvg could work? It seems to be more git-friendly than binary gif?

@moul Looks like the repo has been archived. The concept of SVG is cool, but even though it's indeed a readable format, it ultimately appears to not be that easily readable in this particular sub-format. Also, I don't really like the fact of depending on JavaScript to run.

The key point of VHS is tape files, they are easily maintainable and readable, and you don't have to record it, so the result is always predictable. It also come with cool features like the capacity to produce frame screenshots or integrating hidden parts for a setup phase. If your concern is more about git, it can also produce golden ascii files that are git friendly so we can certainly play around that capacity.

Also, as VHS is written in Go, I have that really distant idea to potentially integrate VHS as a module for txtar. (as external tool ofc) This integration could replace tape file to create GIFs + Screenshot + Markdown Code Block, transforming the doc into a living testing integration 😎