e2e: run the clients against a real cloud

Every gate in this repo compares a client to the document, and every build
proves the client is well-formed. Neither answers the question a user actually
has: does it work against a server. Seven languages now answer it -- go, python,
typescript, dart, php, ruby, rust -- against the local cloud by default and
against anything HANZO_BASE_URL names.

Each probe asserts a 200 whose body decodes AND a 403 that arrives as an error,
because a client that swallows a refusal and returns a zero value looks exactly
like one that works.

It earned its place on the first run: GET /v1/models is AiAPI.GetModels in Go
and ai_api::get_models in Rust but ModelsApi.getModels in TypeScript. One
document, three groupings, and nothing but a call finds it.

e2e/java/E2E.java

@@ -0,0 +1,24 @@
+import ai.hanzo.cloud.*;
+import ai.hanzo.cloud.api.*;
+
+public class E2E {
+    public static void main(String[] a) throws Exception {
+        int fail = 0;
+        ApiClient c = new ApiClient();
+        c.setBasePath(System.getenv("HANZO_BASE_URL"));
+        try {
+            ApiResponse<?> r = new ModelsApi(c).getModelsWithHttpInfo();
+            System.out.println("  ok  GET /v1/models  " + r.getStatusCode());
+        } catch (ApiException e) {
+            System.out.println("  FAIL models: " + e.getCode()); fail++;
+        }
+        try {
+            new EngineApi(c).engineStatus();
+            System.out.println("  FAIL engine: unauthenticated call reported success"); fail++;
+        } catch (ApiException e) {
+            System.out.println("  ok  GET /v1/engine/status refused: " + e.getCode());
+        }
+        System.out.println(fail == 0 ? "PASS java" : "FAIL java (" + fail + ")");
+        System.exit(fail == 0 ? 0 : 1);
+    }
+}