ci(release): build and release a nightly twice a day

- Remove other/nightly, the nightly channel uses the production files, so there are no longer two copies to keep in sync
- sync-cdn.sh --nightly syncs the files of the commit the nightly is built from to /coolify/nightly on the CDN, with the nightly version in its versions.json and in /coolify/release.json, and pushes them straight to main of coollabs-cdn
- version.sh picks the branch the nightly comes from, the release branch of the next version after the newest stable one or next, and names the version <preview>.<YYYYMMDD>.<N>
- The image is labeled with its version and commit, the nightly workflow reads both from the image nightly points at to count up N and to skip a run without a new commit

tests/Unit/InstallScriptDirectoryPermissionsTest.php

@@ -46,7 +46,6 @@ function installScriptFileMode(string $path): string
 
 $installScripts = [
     'stable install' => ['scripts/install.sh', ['source', 'ssh', 'images']],
-    'nightly install' => ['other/nightly/install.sh', ['source', 'ssh', 'images']],
 ];
 $resourceDirectories = ['applications', 'databases', 'backups', 'services', 'proxy', 'sentinel'];