fix(git): remove stale submodule index entries breaking scorecard

C-BJ-awesome-zig and awesome-zig were registered in the git index as
gitlinks (mode 160000) but had no corresponding entries in .gitmodules.
`git submodule foreach` during actions/checkout post-job auth cleanup
hit `fatal: No url found for submodule path 'C-BJ-awesome-zig'` →
exit 128 → startup_failure on every commit, blocking the scorecard
check unconditionally.

Removed both stale index entries with `git rm --cached`.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: hyperpolymath