Use fetch_lib.sh in update script instead of duplicating fallback logic

- Source fetch_lib.sh which handles GitHub → CDN → Local backup
- Check for local fetch_lib.sh first before downloading
- Add CDN fallback for fetch_lib.sh itself
- Cleaner code, no duplication of fallback logic

Author: enoch85

nextcloud_update.sh

@@ -11,22 +11,13 @@
 true
 SCRIPT_NAME="Nextcloud Update Script"
 # shellcheck source=lib.sh
-if ! source <(curl -sL https://raw.githubusercontent.com/nextcloud/vm/main/lib.sh)
+if [ -f /var/scripts/fetch_lib.sh ]
 then
-    # Try Statically.io CDN
-    if source <(curl -sL https://cdn.statically.io/gh/nextcloud/vm/main/lib.sh)
-    then
-        echo "✓ Used Statically.io CDN"
-    # Try local backup
-    elif [ -f /var/scripts/vm-repo-backup/lib.sh ]
-    then
-        echo "⚠ GitHub unavailable, using local backup: lib.sh"
-        # shellcheck source=lib.sh
-        source /var/scripts/vm-repo-backup/lib.sh
-    else
-        echo "Failed to download lib.sh from all sources. Exiting."
-        exit 1
-    fi
+    # shellcheck source=static/fetch_lib.sh
+    source /var/scripts/fetch_lib.sh
+elif ! source <(curl -sL https://raw.githubusercontent.com/nextcloud/vm/main/static/fetch_lib.sh)
+then
+    source <(curl -sL https://cdn.statically.io/gh/nextcloud/vm/main/static/fetch_lib.sh)
 fi
 
 # Get all needed variables from the library