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/InstallScriptAuthorizedKeysTest.php

@@ -38,5 +38,4 @@ it('removes only previous Coolify keys from authorized_keys', function (string $
     exec('rm -rf '.escapeshellarg($home));
 })->with([
     'stable install script' => ['scripts/install.sh'],
-    'nightly install script' => ['other/nightly/install.sh'],
 ]);