fix: derive VER_LOADER from existing symlink on restart

scripts/lib/server.sh

@@ -41,6 +41,20 @@ buildCommand() {
 }
 
 serverStart() {
+  VER_LOADER="${VER_LOADER:-}"
+  if [[ -z "$VER_LOADER" ]]; then
+    if [[ "$MC_LOADER" == "neoforge" ]] && [[ -L "/data/server/server.jar" ]]; then
+      VER_LOADER=$(readlink "/data/server/server.jar" | sed 's/^neoforge-//;s/\.jar$//')
+    elif [[ "$MC_LOADER" == "forge" ]]; then
+      local forge_jar
+      forge_jar=$(ls /data/server/forge-${MC_VERSION}-*.jar 2>/dev/null | head -1)
+      if [[ -n "$forge_jar" ]]; then
+        VER_LOADER=${forge_jar#/data/server/forge-${MC_VERSION}-}
+        VER_LOADER=${VER_LOADER%.jar}
+      fi
+    fi
+  fi
+
   while true; do
     cd /data/server || exit
     if [[ ! -f "server.properties" ]]; then touch "server.properties"; fi