fix(rcon): upsert offline pixel grants

RCON GivePixels previously used an UPDATE for offline users, so users without an existing users_currency type 0 row received no pixels while the command still returned success. Match the GivePoints and housekeeping paths with an upsert and add a contract test that keeps offline pixel grants creating missing currency rows.

Emulator/src/test/java/com/eu/habbo/messages/rcon/GivePixelsContractTest.java

@@ -0,0 +1,24 @@
+package com.eu.habbo.messages.rcon;
+
+import org.junit.jupiter.api.Test;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class GivePixelsContractTest {
+    private static String givePixelsSource() throws Exception {
+        return Files.readString(Path.of("src/main/java/com/eu/habbo/messages/rcon/GivePixels.java"));
+    }
+
+    @Test
+    void offlinePixelGrantCreatesMissingCurrencyRow() throws Exception {
+        String source = givePixelsSource();
+
+        assertTrue(source.contains("INSERT INTO users_currency"),
+                "Offline RCON pixel grants must create the users_currency type 0 row when it is missing");
+        assertTrue(source.contains("ON DUPLICATE KEY UPDATE"),
+                "Offline RCON pixel grants should increment existing rows with an upsert");
+    }
+}