feat(runtime): unregister service revisions

Add a lifecycle-serialized unregister operation that stops a resident Actor before releasing its registered and compiled Component.

Return the existing not-registered and unavailable errors without leaving a partially removed live revision, and cover Actor and registration count cleanup.

crates/wasmeld-runtime/tests/runtime_components.rs

@@ -283,6 +283,23 @@ fn kv_capability_requires_a_backend_and_enforces_limits() {
     runtime.stop(&key).unwrap();
 }
 
+#[test]
+fn unregister_stops_actor_and_releases_compiled_revision() {
+    let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");
+    let key = register_component(&runtime, "unregister", "echo_component.wasm", test_limits());
+    runtime.start(&key, Vec::new()).unwrap();
+
+    runtime.unregister(&key).unwrap();
+
+    let stats = runtime.stats().unwrap();
+    assert_eq!(stats.registered_services, 0);
+    assert_eq!(stats.running_actors, 0);
+    assert!(matches!(
+        runtime.start(&key, Vec::new()),
+        Err(RuntimeError::ServiceNotRegistered(missing)) if missing == key
+    ));
+}
+
 #[test]
 fn registration_rejects_non_whitelisted_wasi_imports() {
     let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");