fix(housekeeping): hash reset password with BCrypt, not SHA-256

`HousekeepingResetUserPasswordEvent` was writing a SHA-256 hex digest
into `users.password`, but the Nitro auth path
(`SessionEndpoints` / `AccountChangeEndpoints` → `AuthHttpUtil.checkPassword`)
only does `BCrypt.checkpw`. A SHA-256 hex string doesn't start with
`$2…$`, so jbcrypt throws `IllegalArgumentException`, `checkPassword`
returns false, and operators saw "credenziali invalide" on every
account whose password had been reset from the in-client panel.

Switch to `BCrypt.hashpw(plain, BCrypt.gensalt(10))` — same idiom
already used by `SessionEndpoints.java:351` and
`AccountChangeEndpoints.java:98`. Cost 10 (vs 12 there) is fine for a
server-generated 12-char random password: gensalt(10) keeps the
operator-facing reset snappy and the output is identical-shape
(`$2a$…`) to what jbcrypt 0.4 already accepts.

Side-effects:
- drops the `MessageDigest` / `NoSuchAlgorithmException` /
  `StandardCharsets` imports and the local `sha256Hex` helper
- repurposes the existing `housekeeping.error.hash_failed` key for
  `BCrypt.gensalt`'s only failure mode (invalid cost / log_rounds out
  of range) so the client error surface is unchanged
- updates the file javadoc to stop telling future readers to "swap the
  MessageDigest constant" — Arcturus itself only verifies BCrypt

Companion of duckietm/Nitro-V3#157 (`feat/housekeeping-panel`). The
client/UI is untouched — packet 9200, the action-result reveal card,
the copy button, and the plaintext flow through `message` are all
unchanged.

Emulator/src/main/java/com/eu/habbo/messages/incoming/housekeeping/HousekeepingResetUserPasswordEvent.java

@@ -4,10 +4,8 @@ import com.eu.habbo.Emulator;
 import com.eu.habbo.habbohotel.permissions.Permission;
 import com.eu.habbo.messages.incoming.MessageHandler;
 import com.eu.habbo.messages.outgoing.housekeeping.HousekeepingActionResultComposer;
+import org.mindrot.jbcrypt.BCrypt;
 
-import java.nio.charset.StandardCharsets;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 import java.sql.Connection;
 import java.sql.PreparedStatement;
@@ -15,19 +13,18 @@ import java.sql.SQLException;
 
 /**
  * Reset a user's password to a fresh random 12-character alphanumeric
- * string. Persists the SHA-256 hex of the new password into
- * `users.password` (varchar(64) — sized to hold SHA-256 hex), clears
- * `auth_ticket` so any active session can't be re-used to bypass the
- * reset, and ships the PLAINTEXT new password back to the operator in
- * the action-result `message` so they can communicate it out-of-band.
- *
- * If your CMS uses a hash other than SHA-256 (bcrypt / argon2 / SHA-1),
- * swap the MessageDigest constant — the rest of the flow is hash-agnostic.
+ * string. Persists a BCrypt `$2a$` hash of the new password into
+ * `users.password` (matches what `AuthHttpUtil.checkPassword` /
+ * `SessionEndpoints` / `AccountChangeEndpoints` already write and read),
+ * clears `auth_ticket` so any active session can't be re-used to bypass
+ * the reset, and ships the PLAINTEXT new password back to the operator
+ * in the action-result `message` so they can communicate it out-of-band.
  */
 public class HousekeepingResetUserPasswordEvent extends MessageHandler {
     private static final String ACTION_KEY = "user.reset_password";
     private static final String PASSWORD_ALPHABET = "ABCDEFGHJKLMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz23456789";
     private static final int PASSWORD_LENGTH = 12;
+    private static final int BCRYPT_COST = 10;
 
     private static final SecureRandom RNG = new SecureRandom();
 
@@ -53,8 +50,8 @@ public class HousekeepingResetUserPasswordEvent extends MessageHandler {
         String hash;
 
         try {
-            hash = sha256Hex(plain);
-        } catch (NoSuchAlgorithmException e) {
+            hash = BCrypt.hashpw(plain, BCrypt.gensalt(BCRYPT_COST));
+        } catch (IllegalArgumentException e) {
             this.client.sendResponse(new HousekeepingActionResultComposer(ACTION_KEY, false, 0, "housekeeping.error.hash_failed"));
             return;
         }
@@ -89,16 +86,4 @@ public class HousekeepingResetUserPasswordEvent extends MessageHandler {
 
         return sb.toString();
     }
-
-    private static String sha256Hex(String plain) throws NoSuchAlgorithmException {
-        MessageDigest md = MessageDigest.getInstance("SHA-256");
-        byte[] digest = md.digest(plain.getBytes(StandardCharsets.UTF_8));
-        StringBuilder hex = new StringBuilder(digest.length * 2);
-
-        for (byte b : digest) {
-            hex.append(String.format("%02x", b));
-        }
-
-        return hex.toString();
-    }
 }