feat: Wire AfterResponseHook through HandlerConfig

Add afterHooks field to HandlerConfig record, add afterHooks list and
afterResponseHook(...) builder method beside interceptor(...), and pass
List.copyOf(afterHooks) into HandlerConfig in build(). Hooks are stored
but not yet fired — execution wiring comes in a later task.

Author: thced

src/main/java/com/retailsvc/http/OpenApiServer.java

@@ -60,7 +60,8 @@ record HandlerConfig(
       ExceptionHandler exceptionHandler,
       Map<String, RequestHandler> extras,
       Map<String, SchemeValidator> securityValidators,
-      boolean externalAuth) {}
+      boolean externalAuth,
+      List<AfterResponseHook> afterHooks) {}
 
   OpenApiServer(
       Spec spec,
@@ -178,6 +179,7 @@ public static final class Builder {
     private Map<String, RequestHandler> handlers;
     private final List<ResponseDecorator> decorators = new ArrayList<>();
     private final List<RequestInterceptor> interceptors = new ArrayList<>();
+    private final List<AfterResponseHook> afterHooks = new ArrayList<>();
     private ExceptionHandler exceptionHandler;
     private int port = DEFAULT_PORT;
     private InetAddress bindAddress;
@@ -228,6 +230,17 @@ public Builder interceptor(RequestInterceptor interceptor) {
       return this;
     }
 
+    /**
+     * Registers an {@link AfterResponseHook} invoked after each response is sent. Hooks run on the
+     * request thread inside the library's request scope, in registration order, with all exceptions
+     * swallowed. Hooks fire only when a {@link Request} was successfully built — pre-request
+     * failures (404, 405, 400 validation) do not fire hooks.
+     */
+    public Builder afterResponseHook(AfterResponseHook hook) {
+      afterHooks.add(requireNonNull(hook, "hook must not be null"));
+      return this;
+    }
+
     /**
      * Registers a {@link SchemeValidator} for the OpenAPI security scheme named {@code schemeName}.
      * The library extracts a {@link Credential} per request and hands it to this callback; return a
@@ -332,7 +345,8 @@ public OpenApiServer build() throws IOException {
               effectiveExceptionHandler,
               extras,
               Map.copyOf(securityValidators),
-              externalAuth);
+              externalAuth,
+              List.copyOf(afterHooks));
       return new OpenApiServer(
           spec, resolved, handlerConfig, port, bindAddress, shutdownTimeoutSeconds);
     }