[0xdhrv]

Authors shouldn't need to know how the duplicate check works, so the comment and job summary no longer name the scorer, TypeSafe, Jev, or Redash.

• The score explanation is now one generic line: "Scores range from 0 to 1 and show how closely an existing extension matches this one."
• Notes about skipped sources are plain: "Store extensions could not be checked this time." and "Open pull requests could not be checked this time."
• When Jev fails and the check falls back to lexical, the comment no longer says so. The existing warning on the workflow run is now the only signal, so maintainers see it there.
• A new test checks that the comment doesn't contain these terms.

To take effect, the workflow in raycast/extensions needs its pinned SHA bumped after this merges.

Tested locally: npm run typecheck, npm test (45 passed), npm run build.