perf(source-control): drop redundant GHES gh auth probe in eligibility

Review follow-up. Detection only routes a GHES remote to the GitHub provider
after getEnterpriseGitHubRepoSlug has confirmed gh is authenticated to its
host, so isGitHubAuthenticated can trust a non-null slug as authenticated and
skip a second, rate-limited `gh auth status` spawn per eligibility poll.
Reaching the github.com probe now implies the remote is github.com. Tests
assert the enterprise path fires no redundant gh probe.

src/main/source-control/hosted-review-creation.test.ts

@@ -388,11 +388,9 @@ describe('createHostedReview', () => {
       url: 'https://github.com/acme/orca/pull/12'
     })
 
-    // The auth probe must target the GHES host, not the hardcoded github.com.
-    expect(ghExecFileAsyncMock).toHaveBeenCalledWith(
-      ['auth', 'status', '--hostname', 'github.acme-corp.com'],
-      { cwd: '/repo' }
-    )
+    // Detection already confirmed gh is authed to the GHES host, so the auth
+    // gate must not fire a second (rate-limited) gh probe.
+    expect(ghExecFileAsyncMock).not.toHaveBeenCalled()
     expect(createGitHubPullRequestMock).toHaveBeenCalled()
     expect(createGiteaPullRequestMock).not.toHaveBeenCalled()
   })
@@ -704,11 +702,9 @@ describe('getHostedReviewCreationEligibility', () => {
       nextAction: null
     })
 
-    // The auth gate must probe the GHES host, not the hardcoded github.com.
-    expect(ghExecFileAsyncMock).toHaveBeenCalledWith(
-      ['auth', 'status', '--hostname', 'github.acme-corp.com'],
-      { cwd: '/repo' }
-    )
+    // Enterprise auth was already confirmed during detection; the gate must not
+    // fire a redundant gh probe.
+    expect(ghExecFileAsyncMock).not.toHaveBeenCalled()
   })
 
   it('resolves remote eligibility through SSH repo metadata without generating PR copy', async () => {

src/main/source-control/hosted-review-creation.ts

@@ -60,15 +60,18 @@ async function isGitHubAuthenticated(
   connectionId?: string | null,
   options: HostedReviewExecutionOptions = {}
 ): Promise<boolean> {
-  // Why: a GHES repo authenticates against its own custom host, so a hardcoded
-  // github.com probe reports "not authenticated" for Enterprise users (#8312).
-  // Resolve the repo's actual GitHub host, defaulting to github.com.
-  const enterprise = await getEnterpriseGitHubRepoSlug(repoPath, connectionId, options)
-  const hostname = enterprise?.host ?? 'github.com'
+  // Why: a GHES remote is only routed to the GitHub provider once detection has
+  // confirmed gh is authenticated to its enterprise host, so a non-null slug
+  // already means authenticated — skip a redundant, rate-limited gh probe.
+  // Reaching the github.com check below therefore means the remote is github.com
+  // (its own custom host would have resolved above) (#8312).
+  if (await getEnterpriseGitHubRepoSlug(repoPath, connectionId, options)) {
+    return true
+  }
   await acquire()
   try {
     await ghExecFileAsync(
-      ['auth', 'status', '--hostname', hostname],
+      ['auth', 'status', '--hostname', 'github.com'],
       connectionId ? {} : { cwd: repoPath, ...getHostedReviewLocalGitOptions(options) }
     )
     return true