refactor(core): migrate to Bun and converge acquisition policies and Agent boundaries

packages/testkit/src/sites/mock-fetch.ts

@@ -21,7 +21,7 @@ export interface MockFetchRequest {
 }
 
 export interface MockFetch {
-  fetch: typeof globalThis.fetch;
+  fetch: (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>;
   requests: MockFetchRequest[];
   /** 追加/覆盖路由 */
   route(key: string, handler: MockRouteHandler): void;
@@ -87,7 +87,7 @@ export function createMockFetch(routes: Record<string, MockRouteHandler> = {}):
     return new Response("not found", { status: 404 });
   };
   return {
-    fetch: fetchImpl as typeof globalThis.fetch,
+    fetch: fetchImpl as (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>,
     requests,
     route(key, handler) {
       table.delete(key);