Add streaming to Engine orchestrator (#6094)

# Description of Changes
Adds a streaming endpoint to the Java AI orchestrator
(`/api/v1/ai/orchestrate/stream` in addition to the existing
`/api/v1/ai/orchestrate`). This allows the caller to get updates of what
stage of orchestration is being run at the time so UIs can give the user
feedback.

Also contains some dubious Gradle changes to suppress errors coming from
Spotless, when it crashes in Google stuff. I'm not sure if that's
appropriate to add, feel free to ask for changes in review.

frontend/src/proprietary/services/apiClientSetup.ts

@@ -95,20 +95,29 @@ async function refreshAuthToken(client: AxiosInstance): Promise<string> {
   }
 }
 
+/** Auth headers for raw fetch() calls (SSE streams, etc.). */
+export function getAuthHeaders(): Record<string, string> {
+  const headers: Record<string, string> = {};
+  const jwt = getJwtTokenFromStorage();
+  if (jwt) {
+    headers["Authorization"] = `Bearer ${jwt}`;
+  }
+  const xsrf = getXsrfToken();
+  if (xsrf) {
+    headers["X-XSRF-TOKEN"] = xsrf;
+  }
+  return headers;
+}
+
 export function setupApiInterceptors(client: AxiosInstance): void {
   // Install request interceptor to add JWT token
   client.interceptors.request.use(
     (config) => {
-      const jwtToken = getJwtTokenFromStorage();
-      const xsrfToken = getXsrfToken();
-
-      if (jwtToken && !config.headers.Authorization) {
-        config.headers.Authorization = `Bearer ${jwtToken}`;
-        console.debug("[API Client] Added JWT token from localStorage to Authorization header");
-      }
-
-      if (xsrfToken && !config.headers["X-XSRF-TOKEN"]) {
-        config.headers["X-XSRF-TOKEN"] = xsrfToken;
+      const authHeaders = getAuthHeaders();
+      for (const [key, value] of Object.entries(authHeaders)) {
+        if (!config.headers[key]) {
+          config.headers[key] = value;
+        }
       }
 
       return config;