After reinstalling the app and importing sources from iCloud, remote
server instances with Keychain-only credentials showed no indication
that login is needed, unlike WebDAV/SMB sources.
- Show the orange key icon for Yattee Server instances without stored
basic auth credentials (auth is always required for this type)
- Persist usesBasicAuth/usesAccountLogin flags on Instance (synced via
iCloud) so missing Invidious/Piped/PeerTube credentials are detectable
too; maintained on credential save/delete, login/logout, and legacy
migration
- Centralize the check in AppEnvironment.needsCredentials(for:) used by
SourcesListView, MediaSourcesView, and SourceRow
- Backfill the flags at launch from credentials currently in the
Keychain so existing setups publish them without a re-login
6994b9353a