chore(husky): add prepare-commit-msg hook for machine-global co-author trailers

Delegates to ~/.config/git/hooks/prepare-commit-msg so
machine-level hooks (co-author trailer injection, etc.)
apply automatically to this repo.

Co-authored-by: Andrew <andrewxhill@gmail.com>

Author: 4ndr3wxh1ll

.husky/prepare-commit-msg

@@ -0,0 +1,3 @@
+#!/bin/sh
+# Machine-global commit hooks (co-author trailer, etc.)
+~/.config/git/hooks/prepare-commit-msg "$@" 2>/dev/null || true