support metamodule, remove built-in overlayfs mount

Co-authored-by: weishu <twsxtd@gmail.com>
Co-authored-by: YuKongA <70465933+YuKongA@users.noreply.github.com>
Co-authored-by: Ylarod <me@ylarod.cn>

userspace/meta-overlayfs/metamodule/metauninstall.sh

@@ -0,0 +1,35 @@
+#!/system/bin/sh
+############################################
+# mm-overlayfs metauninstall.sh
+# Module uninstallation hook for ext4 image cleanup
+############################################
+
+# Constants
+MNT_DIR="/data/adb/metamodule/mnt"
+
+if [ -z "$MODULE_ID" ]; then
+    echo "! Error: MODULE_ID not provided"
+    exit 1
+fi
+
+echo "- Cleaning up module content from image: $MODULE_ID"
+
+# Check if image is mounted
+if ! mountpoint -q "$MNT_DIR" 2>/dev/null; then
+    echo "! Warning: Image not mounted, skipping cleanup"
+    exit 0
+fi
+
+# Remove module content from image
+MOD_IMG_DIR="$MNT_DIR/$MODULE_ID"
+if [ -d "$MOD_IMG_DIR" ]; then
+    echo "  Removing $MOD_IMG_DIR"
+    rm -rf "$MOD_IMG_DIR" || {
+        echo "! Warning: Failed to remove module content from image"
+    }
+    echo "- Module content removed from image"
+else
+    echo "- No module content found in image, skipping"
+fi
+
+exit 0