* Migrate markdownlint-cli to markdownlint-cli2
Replace markdownlint-cli with markdownlint-cli2 and consolidate the three
separate configuration points (.markdownlint.json rules, .markdownlintignore
excludes, and the '**/*.md' glob in the npm scripts) into a single
.markdownlint-cli2.jsonc holding config + globs + ignores.
The npm script names (markdownlint / markdownlint_fix) are unchanged, so the
CI step and the test/fix compound scripts need no change. markdownlint-cli2
v0.23.0 bundles the same markdownlint v0.41.0, so linting behaviour is
identical (112 files, 0 errors).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
* Add JSONC to .editorconfig
* Reduce obvious comments
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Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: Alexandre Alapetite <alexandre@alapetite.fr>