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/kcl-ci/main.k

@@ -669,7 +669,9 @@ fi"""
 # Excludes internal CI config and development history
 # =============================================================================
 _mirror_config = mirror_mod.MirrorBranchConfig {
-    target_branch = "codeberg"
+    remote_url = "git@codeberg.org:vtmocanu/claude-code-action.git"
+    ssh_key_secret = "CODEBERG_MIRROR_SSH_KEY"
+    ssh_host = "codeberg.org"
     exclude_paths = [".forgejo", "prds"]
     paths_ignore = [".forgejo/kcl-ci/**", "prds/**"]
 }