With SessionCreate on the runner's launchd job, standard fastlane keychain
handling works, so drop the debugging-era workarounds: the manual
default-keychain / list-keychains search-list juggling, the login-keychain
restoration in cleanup, the verify_ci_signing re-unlock/partition/find-identity
step (match already imports the cert and sets the key partition list), and the
CODE_SIGN_KEYCHAIN / OTHER_CODE_SIGN_FLAGS xcargs. CI signing is now a single
create_keychain + match. No behavior change; validated end-to-end on TestFlight.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>