Improve redirection

[cthoyt]

• Closes #1034 (fixes issue with leading forward slash in ARKs)
• Fixes issue where a colon might appear in the middle of a CURIE that came up in #1032/#1035 for HGVS terms

[codecov[bot]]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (cec1841) 40.54% compared to head (5ed5302) 40.57%. Report is 1 commits behind head on main.

Files	Patch %	Lines
src/bioregistry/app/ui.py	71.42%	1 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1037 +/- ## ========================================== + Coverage 40.54% 40.57% +0.02% ========================================== Files 148 148 Lines 8237 8244 +7 Branches 1907 1910 +3 ========================================== + Hits 3340 3345 +5 - Misses 4689 4690 +1 - Partials 208 209 +1 ```

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[egonw]

Thanks!