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/rebuild-mfs-test

@@ -0,0 +1,8 @@
+echo '=== MFS WRITE TEST ==='
+touch /storage/.banshee-mergerfs-test
+
+for d in /mnt/banshee/*; do
+  find "$d" -maxdepth 1 -name '.banshee-mergerfs-test' -print
+done
+
+rm /storage/.banshee-mergerfs-test