fix: add missing save mock responses for parallel ACL fetch

The parallel ACL fetching now consumes mock responses that were
previously unused (fallback fetch was skipped when resource ACL
existed). Add a 4th mock response for the saveAclFor step in
the 3 affected "ignores the fallback ACL" tests.

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

Author: maxleonard

src/access/wac.test.ts

@@ -2294,6 +2294,16 @@ describe("setAgentAccess", () => {
           },
           "https://some.pod/.acl",
         ),
+      )
+      // Save the ACL
+      .mockResolvedValueOnce(
+        mockResponse(
+          "",
+          {
+            status: 201,
+          },
+          "https://some.pod/resource.acl",
+        ),
       );
 
     const result = await setAgentResourceAccess(
@@ -3012,6 +3022,16 @@ describe("setGroupResourceAccess", () => {
           },
           "https://some.pod/.acl",
         ),
+      )
+      // Save the ACL
+      .mockResolvedValueOnce(
+        mockResponse(
+          "",
+          {
+            status: 201,
+          },
+          "https://some.pod/resource.acl",
+        ),
       );
 
     const result = await setGroupResourceAccess(
@@ -3695,6 +3715,16 @@ describe("setPublicResourceAccess", () => {
           },
           "https://some.pod/.acl",
         ),
+      )
+      // Save the ACL
+      .mockResolvedValueOnce(
+        mockResponse(
+          "",
+          {
+            status: 201,
+          },
+          "https://some.pod/resource.acl",
+        ),
       );
 
     const result = await setPublicResourceAccess(