Unsigned summary updates left stale summary.sig files on the server,
causing BAD signature errors for clients. Sign exports and summaries
with the BearWave repo key and require .sig files before deploy.
Restore the Flatpak manifest to the repo and target org.kde.Platform
6.10 instead of the EOL 6.6/23.08 stack reported in issue #5.
Add a maintainer build script and a CI job that verifies the manifest
builds against the current KDE SDK.