feat(history-rewrite): Enhance history rewrite process with detailed backup and validation steps

- Added a comprehensive plan for history rewrites in `docs/plans/history_rewrite.md`, including backup requirements and a checklist for destructive operations.
- Created a QA report for history-rewrite scripts in `docs/reports/qa_report.md`, summarizing tests, findings, and recommendations.
- Introduced `check_refs.sh` script to list branches and tags, saving a tarball of tag references.
- Updated `clean_history.sh` to include non-interactive mode and improved error handling for backup branch pushes.
- Enhanced `preview_removals.sh` to support JSON output format and added shallow clone detection.
- Added Bats tests for `clean_history.sh` and `validate_after_rewrite.sh` to ensure functionality and error handling.
- Implemented pre-commit hook to block commits to `data/backups/` directory.
- Improved validation script to check for backup branch existence and run pre-commit checks.
- Created temporary test scripts for validating `clean_history.sh` and `validate_after_rewrite.sh` functionality.

scripts/pre-commit-hooks/block-data-backups-commit.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+
+# Prevent committing any files under data/backups/ accidentally
+staged_files=$(git diff --cached --name-only || true)
+if [ -z "$staged_files" ]; then
+  exit 0
+fi
+
+for f in $staged_files; do
+  case "$f" in
+    data/backups/*)
+      echo "Error: Committing files under data/backups/ is blocked. Remove them from the commit and re-run." >&2
+      exit 1
+      ;;
+  esac
+done
+
+exit 0