refactor(ci): use RPM_REPO_HOST env var, add SSH connectivity test

- Set RPM_REPO_HOST=oolon.kosherinata.internal as a plain env var
  instead of treating the hostname as a secret via RSYNC_TARGET
- Add explicit SSH connectivity test step using StrictHostKeyChecking=accept-new
- Remove ssh-keyscan in favour of accept-new which provides meaningful errors
- Remove RSYNC_TARGET secret dependency

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-release.yml

@@ -159,10 +159,15 @@ jobs:
         run: |
           install --directory --mode 700 ~/.ssh
           echo "${RSYNC_SSH_KEY}" | install --mode 600 /dev/stdin ~/.ssh/id_ed25519
-          ssh-keyscan -H oolon.kosherinata.internal >> ~/.ssh/known_hosts
         env:
           RSYNC_SSH_KEY: ${{ secrets.RSYNC_SSH_KEY }}
 
+      - name: Test SSH connectivity
+        run: |
+          ssh -o StrictHostKeyChecking=accept-new "gitea_ci@${RPM_REPO_HOST}" exit
+        env:
+          RPM_REPO_HOST: oolon.kosherinata.internal
+
       - name: Sync RPMs to repo
         run: |
           rsync \
@@ -170,9 +175,13 @@ jobs:
             --verbose \
             --chmod D755,F644 \
             rpms/*.rpm \
-            "${{ secrets.RSYNC_TARGET }}:/var/www/rpm/fedora/${{ matrix.fedora_version }}/x86_64/"
+            "gitea_ci@${RPM_REPO_HOST}:/var/www/rpm/fedora/${{ matrix.fedora_version }}/x86_64/"
+        env:
+          RPM_REPO_HOST: oolon.kosherinata.internal
 
       - name: Update repo metadata
         run: |
-          ssh "${{ secrets.RSYNC_TARGET }}" \
+          ssh "gitea_ci@${RPM_REPO_HOST}" \
             "cd /var/www/rpm/fedora/${{ matrix.fedora_version }}/x86_64 && createrepo_c --update ."
+        env:
+          RPM_REPO_HOST: oolon.kosherinata.internal