feat: register jira preset in community catalog (#2224)

* feat: register jira preset in community catalog

Adds luno/spec-kit-preset-jira — overrides speckit.taskstoissues to
create Jira issues instead of GitHub Issues.

See #2223 for context on why this is a preset rather than an extension.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: use immutable tag URL and sort jira preset alphabetically

- Change download_url from heads/main to refs/tags/v1.0.0 for reproducible installs
- Move jira entry to correct alphabetical position in presets object

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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Co-authored-by: Ed Harrod <1381991+echarrod@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>