Fix CI: stub @cloudflare/sandbox and @cloudflare/containers in tests

workerd cannot resolve @cloudflare/containers (imported by @cloudflare/sandbox)
at runtime. Alias both to an empty stub module in vitest config to avoid
module resolution failures in tests that don't exercise these bindings.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: bchapuis

apps/api/test/stubs/empty-module.ts

@@ -0,0 +1,3 @@
+// Empty stub for packages that can't be resolved in the workerd test environment.
+// Used by vitest.config.ts resolve.alias to avoid module resolution failures.
+export default {};

apps/api/vitest.config.ts

@@ -1,6 +1,18 @@
+import path from "node:path";
 import { defineWorkersConfig } from "@cloudflare/vitest-pool-workers/config";
 
+const emptyStub = path.resolve(__dirname, "test/stubs/empty-module.ts");
+
 export default defineWorkersConfig({
+  resolve: {
+    alias: {
+      // @cloudflare/sandbox imports @cloudflare/containers which workerd
+      // cannot resolve at runtime. Stubbing both avoids module resolution
+      // failures in tests that don't exercise these bindings.
+      "@cloudflare/sandbox": emptyStub,
+      "@cloudflare/containers": emptyStub,
+    },
+  },
   test: {
     setupFiles: ["./test/setup.ts"],
     testTimeout: 30000,