fix: align survey kfc tests with CUSTOM_API managed URL

isManagedPythinkerCodeBaseUrl only matches CUSTOM_API_BASE_URL. Point
survey kfc fixtures at that env so pfc_model_id and pfc_trace_id resolve.
Annotate the shared session-event host helper return type for tsc.

Author: elkaix

apps/pythinker-code/test/tui/controllers/session-event-handler-host.ts

@@ -10,7 +10,11 @@ type HostOverrides = {
   [key: string]: unknown;
 };
 
-export function makeSessionEventHandlerHost(overrides: HostOverrides = {}) {
+export function makeSessionEventHandlerHost(overrides: HostOverrides = {}): {
+  readonly host: never;
+  readonly streamingUI: never;
+  readonly surveyController: never;
+} {
   const streamingUI = {
     setTurnId: vi.fn(),
     flushNow: vi.fn(),
@@ -89,5 +93,5 @@ export function makeSessionEventHandlerHost(overrides: HostOverrides = {}) {
     ...rest,
   };
 
-  return { host: host as never, streamingUI, surveyController };
+  return { host: host as never, streamingUI: streamingUI as never, surveyController: surveyController as never };
 }

apps/pythinker-code/test/tui/controllers/survey-controller.test.ts

@@ -763,7 +763,7 @@ describe('SurveyController kfc model gate', () => {
   const savedBaseUrl = process.env['CUSTOM_API_BASE_URL'];
 
   beforeEach(() => {
-    delete process.env['CUSTOM_API_BASE_URL'];
+    process.env['CUSTOM_API_BASE_URL'] = MANAGED_BASE_URL;
   });
 
   afterEach(() => {
@@ -2167,7 +2167,7 @@ describe('SurveyController appearance snapshot', () => {
   const savedBaseUrl = process.env['CUSTOM_API_BASE_URL'];
 
   beforeEach(() => {
-    delete process.env['CUSTOM_API_BASE_URL'];
+    process.env['CUSTOM_API_BASE_URL'] = MANAGED_BASE_URL;
   });
 
   afterEach(() => {