Added shared update notices

- Iris joins shared Volmit update checks and reports
- The iris.update permission controls update visibility
- general.updateNotifications defaults to enabled
- Accepted settings changes reconfigure update checks
- Shutdown removes the settings listener and closes update checks
- Tests cover persisted opt-outs and notifier lifecycle

adapters/bukkit/plugin/src/test/java/art/arcane/iris/update/IrisUpdateNotifierTest.java

@@ -0,0 +1,61 @@
+package art.arcane.iris.update;
+
+import art.arcane.iris.configuration.IrisSettings;
+import art.arcane.volmlib.util.update.BukkitUpdateService;
+import org.bukkit.plugin.Plugin;
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.MockedStatic;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.clearInvocations;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+
+public class IrisUpdateNotifierTest {
+    @Test
+    public void acceptedSettingsReconfigureChecksAndClosingRemovesTheListener() {
+        IrisSettings previous = IrisSettings.settings;
+        IrisSettings.settings = new IrisSettings();
+        Plugin plugin = mock(Plugin.class);
+        BukkitUpdateService service = mock(BukkitUpdateService.class);
+        try (MockedStatic<BukkitUpdateService> registration = mockStatic(BukkitUpdateService.class)) {
+            registration.when(() -> BukkitUpdateService.register(eq(plugin), any())).thenReturn(service);
+            IrisUpdateNotifier notifier = new IrisUpdateNotifier(plugin);
+            try {
+                ArgumentCaptor<BukkitUpdateService.Options> options = ArgumentCaptor.forClass(BukkitUpdateService.Options.class);
+                registration.verify(() -> BukkitUpdateService.register(eq(plugin), options.capture()));
+                assertEquals("VolmitSoftware", options.getValue().owner());
+                assertEquals("Iris", options.getValue().repository());
+                assertEquals("iris.update", options.getValue().permission());
+                assertTrue(options.getValue().enabled().getAsBoolean());
+
+                clearInvocations(service);
+                assertFalse(IrisSettings.applyHotloadSnapshot(
+                        "{\"general\":{\"updateNotifications\":false}}", candidate -> false));
+                assertTrue(options.getValue().enabled().getAsBoolean());
+                verifyNoInteractions(service);
+
+                IrisSettings.installHotloadSnapshot("{\"general\":{\"updateNotifications\":false}}");
+                assertFalse(options.getValue().enabled().getAsBoolean());
+                verify(service).reconfigure();
+                IrisSettings.settings.getGeneral().setUpdateNotifications(true);
+                assertFalse(options.getValue().enabled().getAsBoolean());
+            } finally {
+                notifier.close();
+            }
+            verify(service).close();
+            clearInvocations(service);
+            IrisSettings.installHotloadSnapshot("{}");
+            verifyNoInteractions(service);
+        } finally {
+            IrisSettings.settings = previous;
+        }
+    }
+}