docs: use upstream APIs

[flying-sheep]

Switches to upstream myst-nb and switches from monkeypatching to public APIs to implement the “skip mime types” extension: https://myst-nb.readthedocs.io/en/latest/render/format_code_cells.html#customise-the-render-process

• Closes #
• Tests included or not required because:

• Release notes not necessary because: docs change only

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.60%. Comparing base (bb617ba) to head (9ca9dba).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4083      +/-   ##
==========================================
+ Coverage   78.58%   78.60%   +0.02%     
==========================================
  Files         118      118              
  Lines       12753    12753              
==========================================
+ Hits        10022    10025       +3     
+ Misses       2731     2728       -3     

Flag	Coverage Δ
hatch-test.low-vers	77.91% <ø> (ø)
hatch-test.pre	78.49% <ø> (+11.19%)	⬆️

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see 1 file with indirect coverage changes