fix(hooks): use portable for loop instead of process substitution in pre-push

The process substitution syntax `< <(...)` is bash-specific and causes
syntax errors when Git invokes the hook with sh on some systems.

Changed from:
  while IFS= read -r commit_sha; do
    ...
  done < <(git rev-list "$range")

To portable sh-compatible for loop:
  for commit_sha in $(git rev-list "$range"); do
    ...
  done

This solution:
- Works with any POSIX shell (sh, bash, dash, etc.)
- Avoids subshell creation (unlike pipe)
- Correctly propagates ERRORS variable to parent scope
- Fixes AI attribution detection that was failing silently

Author: jdalton

.husky/pre-push

@@ -56,7 +56,8 @@ while read local_ref local_sha remote_ref remote_sha; do
   printf "Checking commit messages for AI attribution...\n"
 
   # Check each commit in the range for AI patterns.
-  while IFS= read -r commit_sha; do
+  # Use for loop instead of while to avoid subshell (pipe) or bash-only syntax (process substitution).
+  for commit_sha in $(git rev-list "$range"); do
     full_msg=$(git log -1 --format='%B' "$commit_sha")
 
     if echo "$full_msg" | grep -qiE "(Generated with.*(Claude|AI)|Co-Authored-By: Claude|Co-Authored-By: AI|🤖 Generated|AI generated|@anthropic\.com|Assistant:|Generated by Claude|Machine generated)"; then
@@ -67,7 +68,7 @@ while read local_ref local_sha remote_ref remote_sha; do
       echo "  - $(git log -1 --oneline "$commit_sha")"
       ERRORS=$((ERRORS + 1))
     fi
-  done < <(git rev-list "$range")
+  done
 
   if [ $ERRORS -gt 0 ]; then
     printf "\n"