fix(storage): fix FormatAndMount for container environment

Bug 1 (sfdisk): Add wipefs before sfdisk; change partition type from
,,,L (unsupported GPT shorthand) to ,, (default Linux GUID); add
--force --wipe always flags to handle existing partition tables.

Bug 2 (mount): Replace fstab-lookup mount with explicit device path:
  mount -t ext4 -o defaults,noatime /host-dev/sdb1 /mnt/hdd_1
Container's /etc/fstab is Docker's auto-generated one, not the host's.

Bug 3 (mount propagation): Change /mnt volume to long-form bind with
propagation: rshared so mounts created inside container propagate to
the host. Requires mount --make-rshared /mnt on host before restart.

Safety: Use req.MountName (ASCII) for ext4 -L label (16-byte limit;
UTF-8 display label stays in settings.json). Add findmnt verification
after mount. Improve progress messages with command details.

Smart partition: In storageInitAPIHandler, if disk already has exactly
1 empty partition (no filesystem), skip wipefs+sfdisk and format the
existing partition directly.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

controller/docker-compose.yml

@@ -22,8 +22,13 @@ services:
       - /opt/docker/stacks:/opt/docker/stacks
       # Backup directories (restic repo + db dumps)
       - /srv/backups:/srv/backups
-      # All external storage — /mnt/* for multi-storage + restore
-      - /mnt:/mnt:rw
+      # All external storage — rshared propagation so mounts created inside
+      # the container (disk init) propagate to the host and vice versa
+      - type: bind
+        source: /mnt
+        target: /mnt
+        bind:
+          propagation: rshared
       # Host /sys — for CPU temperature reading (read-only)
       - /sys:/host/sys:ro
       # Host OS info — for monitoring page system info