Add Khmer (README.km.md) to all 17 other translations' language
selectors. Fix README.km.md: add translation disclaimer, download
badge in Install section, translate feature table headings/descriptions
and browser section note from English to Khmer.
* Create README-kh.md for Khmer localization
Add Khmer language support to README
* Address review feedback: rename to README.km.md, add screenshots/star history
- Rename README-kh.md to README.km.md (correct ISO 639-1 language code, dot separator)
- Add Khmer link to main README.md language switcher
- Add feature screenshot table matching original README structure
- Add browser keyboard shortcuts note
- Add Star History section
- Use relative image paths consistent with other localized READMEs
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Co-authored-by: im4tta <82812618+im4tta@users.noreply.github.com>
