fix: make backing up robust and lengthen discord ping

modules/backup.nix

@@ -27,16 +27,16 @@ in
         sleep 2
         docker exec minecraft rcon-cli save-off
 
-        # Compress world data (re-enable saving even if tar fails)
-        if ! ${pkgs.gnutar}/bin/tar czf "$TEMP_BACKUP" \
-          -C ${mcDataDir} world; then
-          echo "tar failed, re-enabling saving"
-          docker exec minecraft rcon-cli save-on
-          exit 1
-        fi
+        # Ensure save-on runs no matter how the script exits from here
+        trap 'docker exec minecraft rcon-cli save-on' EXIT
 
-        # Re-enable saving immediately
+        # Compress world data
+        ${pkgs.gnutar}/bin/tar czf "$TEMP_BACKUP" \
+          -C ${mcDataDir} world
+
+        # Re-enable saving immediately (trap will also fire, but save-on is idempotent)
         docker exec minecraft rcon-cli save-on
+        trap - EXIT
 
         # Upload to B2 (overwrites the single backup file)
         B2_ACCOUNT=$(cat ${config.age.secrets.b2-account-id.path})
@@ -47,8 +47,17 @@ in
           ":b2:${b2Bucket}/world-latest.tar.gz" \
           --b2-account "$B2_ACCOUNT" \
           --b2-key "$B2_KEY" \
+          --b2-hard-delete \
+          --config /dev/null \
           --no-check-dest
 
+        # Purge old file versions to stay under storage cap
+        ${pkgs.rclone}/bin/rclone cleanup \
+          ":b2:${b2Bucket}" \
+          --b2-account "$B2_ACCOUNT" \
+          --b2-key "$B2_KEY" \
+          --config /dev/null
+
         # Clean up local temp file
         rm -f "$TEMP_BACKUP"