* feat: support artalk comment system
* chore: change url from testingcf to cdn prefix
* refactor(comments): align artalk provider style and keep custom css overrides
* fix: update Artalk CDN links to use the correct URL
* refactor(comments): simplify Artalk implementation
* fix(artalk): update script tag to use ESM for Artalk
* fix(artalk): set locale to 'auto' for Artalk comments
* refactor: move artalk style and script link to external.toml
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Co-authored-by: Jimmy Cai <jimmy@cai.im>
