Add scripts and configuration files for mergerfs setup and testing

- Created backup files for wipefs on specific disk partitions.
- Added db-test script to verify metadata.db file integrity.
- Documented successful mergerfs branch and pool configurations in mfs-good.txt.
- Implemented mfs write test in mfs-test.txt.
- Included mergerfs version and device information in mfs.txt.
- Developed rebuild scripts for mergerfs stages, including verification and filesystem creation.
- Generated stage logs for each rebuild step to track disk and filesystem status.
- Added checks for systemd mount requirements and filesystem verification in stage4.

post-rebuild/db-test

@@ -0,0 +1,20 @@
+cd "/storage/Warez/Books/Calibre"
+
+for f in \
+  metadata.db
+do
+  echo "=== $f ==="
+  getfattr --only-values -n user.mergerfs.fullpath "$f"
+  echo
+done
+
+for f in \
+  metadata.db
+do
+  p=$(getfattr --only-values -n user.mergerfs.fullpath "$f")
+
+  echo
+  echo "=== $p ==="
+
+  sqlite3 "$p" 'PRAGMA integrity_check;'
+done