flutter pub get was not being cached by Dagger because the pub-cache
CacheVolume used Shared mode: concurrent writes from the check and
deploy-playstore jobs made the mount non-deterministic, causing a cache
miss on every run. Locked mode gives each operation exclusive access so
the output snapshot is stable and Dagger can cache subsequent steps.
Also add --no-pub to both flutter build commands: pub get already ran
explicitly in Setup(), so skipping it again inside the build step avoids
a duplicate network-touching operation.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
