Add Hytale reason-to-message resolver for revocation UX

Author: LegendaryForge

src/main/java/io/github/legendaryforge/legendary/core/internal/platform/hytale/LegendaryReasonMessageResolver.java

@@ -0,0 +1,23 @@
+package io.github.legendaryforge.legendary.core.internal.platform.hytale;
+
+import io.github.legendaryforge.legendary.core.api.id.ResourceId;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Platform-side mapping from core reason IDs to player-facing messages.
+ *
+ * <p>Core emits stable reason IDs. Platforms decide how to present them.
+ */
+public final class LegendaryReasonMessageResolver {
+
+    private static final Map<ResourceId, String> MESSAGES =
+            Map.of(new ResourceId("legendary", "out_of_bounds"), "Participation revoked: left arena bounds.");
+
+    private LegendaryReasonMessageResolver() {}
+
+    public static String messageFor(ResourceId reasonId) {
+        Objects.requireNonNull(reasonId, "reasonId");
+        return MESSAGES.getOrDefault(reasonId, "Participation revoked.");
+    }
+}

src/test/java/io/github/legendaryforge/legendary/core/internal/platform/hytale/LegendaryReasonMessageResolverTest.java

@@ -0,0 +1,21 @@
+package io.github.legendaryforge.legendary.core.internal.platform.hytale;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import io.github.legendaryforge.legendary.core.api.id.ResourceId;
+import org.junit.jupiter.api.Test;
+
+final class LegendaryReasonMessageResolverTest {
+
+    @Test
+    void knownReasonResolvesToSpecificMessage() {
+        String msg = LegendaryReasonMessageResolver.messageFor(new ResourceId("legendary", "out_of_bounds"));
+        assertEquals("Participation revoked: left arena bounds.", msg);
+    }
+
+    @Test
+    void unknownReasonFallsBackToGenericMessage() {
+        String msg = LegendaryReasonMessageResolver.messageFor(new ResourceId("legendary", "unknown"));
+        assertEquals("Participation revoked.", msg);
+    }
+}