fix(auth): move SecureRandom out of static field for native-image compat

GraalVM native-image rejects static fields of type Random/SecureRandom
(their internal state is captured at build time and can't be replayed
deterministically). Move the instance into generatePassword() as a
local variable - it is only used once at startup anyway.

src/main/java/com/l2/shots/auth/BootstrapAdmin.java

@@ -21,7 +21,6 @@ import java.security.SecureRandom;
 public class BootstrapAdmin {
 
     private static final Logger LOG = Logger.getLogger(BootstrapAdmin.class);
-    private static final SecureRandom RANDOM = new SecureRandom();
     // Alfabeto sin chars ambiguos (0/o/O, 1/l/I) para no cansar al tipear.
     private static final char[] ALPHABET =
             "ABCDEFGHJKLMNPQRSTUVWXYZ23456789abcdefghjkmnpqrstuvwxyz".toCharArray();
@@ -61,9 +60,12 @@ public class BootstrapAdmin {
     }
 
     private static String generatePassword() {
+        // Local para evitar un campo estático (GraalVM native-image no permite
+        // instancias de Random/SecureRandom en el image heap; las crea en runtime).
+        SecureRandom random = new SecureRandom();
         StringBuilder sb = new StringBuilder(PASSWORD_LENGTH);
         for (int i = 0; i < PASSWORD_LENGTH; i++) {
-            sb.append(ALPHABET[RANDOM.nextInt(ALPHABET.length)]);
+            sb.append(ALPHABET[random.nextInt(ALPHABET.length)]);
         }
         return sb.toString();
     }