Update environment example, enhance copilot instructions, and add release skills documentation

scripts/publish-image.sh

@@ -24,6 +24,32 @@ fi
 
 cd "$repo_root"
 docker build --tag "$image:$version" --tag "$image:latest" .
+registry_username="${GITEA_USERNAME:-${DOCKER_USERNAME:-}}"
+registry_token="${GITEA_TOKEN:-${DOCKER_PASSWORD:-}}"
+unset GITEA_TOKEN DOCKER_PASSWORD
+env_file="$repo_root/.env"
+if [[ -f "$env_file" ]]; then
+  while IFS= read -r line || [[ -n "$line" ]]; do
+    line="${line%$'\r'}"
+    if [[ "$line" =~ ^GITEA_USERNAME=(.*)$ ]]; then
+      registry_username="${BASH_REMATCH[1]}"
+    elif [[ "$line" =~ ^GITEA_TOKEN=(.*)$ ]]; then
+      registry_token="${BASH_REMATCH[1]}"
+    fi
+  done < "$env_file"
+fi
+
+if [[ -n "$registry_username" || -n "$registry_token" ]]; then
+  if [[ -z "$registry_username" || -z "$registry_token" ]]; then
+    echo "Set both GITEA_USERNAME and GITEA_TOKEN in .env to log in automatically." >&2
+    exit 1
+  fi
+  if ! printf '%s' "$registry_token" | docker login --username "$registry_username" --password-stdin gitea.faerro.it; then
+    unset registry_token
+    exit 1
+  fi
+  unset registry_token
+fi
 docker push "$image:$version"
 docker push "$image:latest"