Point the last rehearsal at the credential that still exists

`orbit-slice5-images-cpu-staging-e2e.ts` builds a throwaway Worker config
and reads its secrets from the Keychain by name, and two of those names
were GitHub's. Nothing caught it because the script is hand-run — it is on
the deliberate list of rehearsals that cannot run nightly, since it burns
Cloudflare Images quota. So the failure would have waited until the next
time someone reached for it, and arrived as a missing Keychain item rather
than as anything explaining itself.

The dead secrets are now deleted from both Workers, production and
staging. Verified afterwards that sign-in still starts, the health check
answers, and a profile renders.

Local proof: `npm run build` end to end.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: sametbasbug

scripts/orbit-slice5-images-cpu-staging-e2e.ts

@@ -131,8 +131,8 @@ const mediaIds: string[] = [];
 const phaseSamples: Record<string, number[]> = {};
 try {
   const secretNames = [
-    'GITHUB_OAUTH_CLIENT_ID',
-    'GITHUB_OAUTH_CLIENT_SECRET',
+    'GOOGLE_OAUTH_CLIENT_ID',
+    'GOOGLE_OAUTH_CLIENT_SECRET',
     'ORBIT_INVITATION_PEPPER_V1',
     'ORBIT_SESSION_PEPPER_V1',
     'ORBIT_AGENT_CREDENTIAL_PEPPER_V1',