fix deploy-rs: set sshUser=root explicitly, fix host key verification

deploy-rs was using 'gitea-runner' as ssh_user because the runner
process runs as that user. Set sshUser=root at the node level.
Also add StrictHostKeyChecking=accept-new as fallback for host key.

.forgejo/workflows/deploy.yml

@@ -30,9 +30,10 @@ jobs:
           echo "$DEPLOY_KEY" > ~/.ssh/id_ed25519
           chmod 600 ~/.ssh/id_ed25519
           ssh-keyscan -p 2299 -H cryodev.xyz >> ~/.ssh/known_hosts
+          chmod 644 ~/.ssh/known_hosts
 
       - name: Deploy with deploy-rs
-        run: nix run github:serokell/deploy-rs -- -s .#cryodev-main
+        run: NIX_SSHOPTS="-p 2299 -o StrictHostKeyChecking=accept-new" nix run github:serokell/deploy-rs -- -s .#cryodev-main
 
   build-pi-images:
     needs: flake-check

flake.nix

@@ -123,6 +123,7 @@
         nodes = {
           cryodev-main = {
             hostname = constants.domain;
+            sshUser = "root";
             sshOpts = [
               "-p"
               "2299"