fix(ci): cross-validate and fix tracker workflow — 4 bugs squashed

Bug fixes found during cross-validation:

1. VERSION-INSERT marker placed before table header → moved after separator
   line so new rows insert between separator and first data row.

2. Badge sed pattern 'tested\)-[0-9a-z.]*\(blue\)' never matched because
   URL has 'tested-blue' not 'tested)-...'. Fixed to match URL-encoded
   format: '%20<version>%20tested-blue'.

3. Quick Reference sed depended on '| ✅' status literal. Changed to
   '| [^|]*' to match any status text, always setting to ⏳ on update.

4. Gitea API returns 'v1.27.0' tag_name but docs use '1.27.0'. Added
   '${NEW_VERSION#v}' to strip v prefix.

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

COMPATIBILITY.md

@@ -21,9 +21,9 @@ gitea --version
 
 ## Gitea Version History — Mail Template Impact
 
-<!-- TRACKER:VERSION-INSERT -->
 | Gitea | Release Date | Mail Template Changes | Breaking? |
 |-------|-------------|----------------------|-----------|
+<!-- TRACKER:VERSION-INSERT -->
 | **1.26.4** | 2026-06-21 | None — hotfix release | No |
 | **1.26.3** | 2026-06-20 | None — security release | No |
 | **1.26.2** | 2026-05-20 | None — security + bug fixes | No |