Add routing rules management to repository settings

[brandonrc]

Backend: artifact-keeper/artifact-keeper#662

Raw/generic remote repos now support URL path rewriting via routing rules. The frontend needs:

1. A 'Routing Rules' tab in repo settings (for remote raw/generic repos only)
2. List existing rules with path pattern and rewrite template
3. Add/delete rules with regex validation feedback
4. Example helper showing the GitHub Releases proxy use case

API: GET/POST/DELETE /api/v1/repositories/{key}/routing-rules

[brandonrc]

Fixed in v1.2.0. This shipped via the release integration PR #466 (v1.2.0) and is live on main. It was listed in #466's body but GitHub did not auto-close it: the body used a single Closes keyword followed by many issue numbers, and GitHub only auto-closes the first (#424) in that form. Closing manually.