test(acp): use the shared auth stubs in the three harnesses that missed them

auth-gate, session-load and session-resume imported AUTHED/UNAUTHED but
still hand-rolled `isAuthenticated`, leaving the imports dead. auth-gate
was already half-converted (the inline harness uses UNAUTHED), so this
finishes what 1456fb2 started and matches the 18 sibling test files.

Author: elkaix

packages/acp-adapter/test/auth-gate.test.ts

@@ -47,7 +47,7 @@ function makeInMemoryStreamPair(): {
 
 function makeHarnessWithToken(hasToken: boolean): PythinkerHarness {
   return {
-    isAuthenticated: async () => hasToken,
+    isAuthenticated: hasToken ? AUTHED : UNAUTHED,
   } as unknown as PythinkerHarness;
 }
 

packages/acp-adapter/test/session-load.test.ts

@@ -89,7 +89,7 @@ function makeHarness(
 ): PythinkerHarness {
   const authed = opts.hasUsableToken ?? true;
   return {
-    isAuthenticated: async () => authed,
+    isAuthenticated: authed ? AUTHED : UNAUTHED,
     resumeSession: async (_input: { id: string }) => {
       if (opts.resumeError) throw opts.resumeError;
       if (!opts.session) throw new Error('test harness has no session configured');

packages/acp-adapter/test/session-resume.test.ts

@@ -104,7 +104,7 @@ function makeHarness(opts: {
 }): PythinkerHarness {
   const authed = opts.hasUsableToken ?? true;
   return {
-    isAuthenticated: async () => authed,
+    isAuthenticated: authed ? AUTHED : UNAUTHED,
     resumeSession: async (_input: { id: string }) => {
       if (opts.resumeError) throw opts.resumeError;
       if (!opts.session) throw new Error('test harness has no session configured');