The cache marker hashed only sources, so switching signing team or key
reused a runner signed with the stale identity, which the device rejects at
install (0xe8008018). Fold team + key id into the cache key so a signing
change forces a rebuild.
companion/project.yml disables code signing for the simulator build, so
the device build inherited it and produced an unsigned runner that the
device rejected at install (0xe8008018). build-for-testing now forces
CODE_SIGNING_ALLOWED/REQUIRED=YES so automatic provisioning signs it.
xcodebuild's -authenticationKeyPath requires an absolute path, but .env
files commonly carry a repo-relative one. Resolve it against the working
directory before the stat so a relative ASC_API_KEY_PATH still signs.