Add Catalog CI extension to community catalog (#2239)

- Adds catalog-ci entry to catalog.community.json (between canon and ci-guard)
- Adds Catalog CI row to community extensions table in README.md
- Bumps top-level updated_at

README.md

@@ -199,6 +199,7 @@ The following community-contributed extensions are available in [`catalog.commun
 | Brownfield Bootstrap | Bootstrap spec-kit for existing codebases — auto-discover architecture and adopt SDD incrementally | `process` | Read+Write | [spec-kit-brownfield](https://github.com/Quratulain-bilal/spec-kit-brownfield) |
 | Bugfix Workflow | Structured bugfix workflow — capture bugs, trace to spec artifacts, and patch specs surgically | `process` | Read+Write | [spec-kit-bugfix](https://github.com/Quratulain-bilal/spec-kit-bugfix) |
 | Canon | Adds canon-driven (baseline-driven) workflows: spec-first, code-first, spec-drift. Requires Canon Core preset installation. | `process` | Read+Write | [spec-kit-canon](https://github.com/maximiliamus/spec-kit-canon/tree/master/extension) |
+| Catalog CI | Automated validation for spec-kit community catalog entries — structure, URLs, diffs, and linting | `process` | Read-only | [spec-kit-catalog-ci](https://github.com/Quratulain-bilal/spec-kit-catalog-ci) |
 | CI Guard | Spec compliance gates for CI/CD — verify specs exist, check drift, and block merges on gaps | `process` | Read-only | [spec-kit-ci-guard](https://github.com/Quratulain-bilal/spec-kit-ci-guard) |
 | Checkpoint Extension | Commit the changes made during the middle of the implementation, so you don't end up with just one very large commit at the end | `code` | Read+Write | [spec-kit-checkpoint](https://github.com/aaronrsun/spec-kit-checkpoint) |
 | Cleanup Extension | Post-implementation quality gate that reviews changes, fixes small issues (scout rule), creates tasks for medium issues, and generates analysis for large issues | `code` | Read+Write | [spec-kit-cleanup](https://github.com/dsrednicki/spec-kit-cleanup) |