The release preflight used to set should_build_platform=false whenever any
Apple signing secret was unset, which silently skipped the entire macos dmg
and ios ipa lanes (build + upload gated on that flag). Result: releases only
shipped linux, windows and android artifacts even when the iOS/macOS lanes
were otherwise healthy.
Make the preflight always release the lane, but emit a :⚠️: and
annotate the skip_reason when a secret is missing. The iOS branch in
build_matrix_artifacts.sh now picks the signed vs unsigned build path based
on actual secret availability instead of should_release alone, so it falls
back to flutter build ios --no-codesign + zip Runner.app whenever a secret
is absent. package-flutter-mac-app.sh already handled the no-secret case
locally (ad-hoc codesign --sign -) and needs no change.
Behavior matrix:
macos: secret present -> signed DMG; secret missing -> unsigned DMG
ios: secret present + release -> signed IPA
secret present + non-release -> unsigned zip
secret missing (any) -> unsigned zip
