Two diagnostics faults from #313, fixed together:
1. Dead push trigger. build.yml and flutter_dart.yml declared
`push: branches: [main]`, but no `main` branch exists in this
repo (default is `dev`), so the push half of every trigger had
never fired. Nothing built on merge. Added `dev` to both; `main`
is created separately after this merges.
2. No artifacts. All six platform jobs stopped at `flutter build`,
so every binary CI produced was discarded with the runner. Added
actions/upload-artifact to the four jobs that produce something
installable or servable:
android build/app/outputs/flutter-apk/app-release.apk
windows build/windows/x64/runner/Release/
linux build/linux/x64/release/bundle/
web build/web/
ios and macos are compile checks only and upload nothing: ios is
built --no-codesign so it is not installable, and macos is kept
as a compile check per the owner's decision on #321.
Artifacts carry run number + commit SHA so a build traces back to a
commit, and use if-no-files-found: error so a wrong path fails loudly
rather than silently publishing an empty artifact.
Android artifacts are debug-signed for now; real signing is Phase 5.
The web artifact is the plain `flutter build web` output, not the
build_pipe versioned build used for deploys; Phase 4 addresses that.
Part of epic #312, plan #321 (Phase 1, owner-approved).
Strycher
8ea5ede1dc