chore(web): remove unused @clerk/themes dependency

The auth modal now uses @clerk/ui/themes' stock dark theme, so the legacy
@clerk/themes package is no longer imported.

Author: iamjr15

apps/web/package.json

@@ -18,7 +18,6 @@
     "@cheatcode/types": "workspace:*",
     "@cheatcode/ui": "workspace:*",
     "@clerk/nextjs": "catalog:",
-    "@clerk/themes": "^2.4.57",
     "@clerk/ui": "catalog:",
     "@hookform/resolvers": "catalog:",
     "@streamdown/code": "catalog:",