feat: mirror to Codeberg via SSH deploy key

Push clean copy (without .forgejo/ and prds/) to Codeberg on
each push to main. Uses SSH deploy key for authentication.

Also bumps kcl-ci to v1.40.0.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.forgejo/workflows/kcl-ci-build.yml

@@ -1,4 +1,4 @@
-# Generated by KCL v1.38.0 - DO NOT EDIT
+# Generated by KCL v1.40.0 - DO NOT EDIT
 # Source: .forgejo/kcl-ci/main.k
 # kcl-ci local: ~/stuff/gitrepos/wxs/actions/kcl-ci
 # kcl-ci remote: https://git.wxs.ro/actions/kcl-ci
@@ -21,7 +21,7 @@ jobs:
     runs-on: grunt
     steps:
     - name: Build KCL workflows
-      uses: https://${{ secrets.READ_REPO_TOKEN }}@git.wxs.ro/actions/kcl-ci@v1.38.0
+      uses: https://${{ secrets.READ_REPO_TOKEN }}@git.wxs.ro/actions/kcl-ci@v1.40.0
       with:
         read-repo-token: ${{ secrets.READ_REPO_TOKEN }}
         working-dir: '.forgejo/kcl-ci'