Replace the `@github/relative-time-element` npm dependency with a
vendored, simplified implementation.
- Support 24h format rendering [PR
329](https://github.com/github/relative-time-element/pull/329)
- Enable `::selection` styling in Firefox [PR
341](https://github.com/github/relative-time-element/pull/341)
- Remove timezone from tooltips (It's always local timezone)
- Clean up previous `title` workaround in tippy
- Remove unused features
- Use native `Intl.DurationFormat` with fallback for older browsers,
remove dead polyfill
- Add MIT license header to vendored file
- Add unit tests
- Add dedicated devtest page for all component variants
---------
Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: Claude claude-opus-4-6 20250630 <noreply@anthropic.com>
None of the frontend js/ts files was touched besides these two commands
(edit: no longer true, I touched one file in
61105d0618
because of a deprecation that was not showing before the rename).
`tsc` currently reports 778 errors, so I have disabled it in CI as
planned.
Everything appears to work fine.