refactor: enhance Gitea registry login with fallback credentials and error handling

.gitea/workflows/publish-image.yml

@@ -41,8 +41,29 @@ jobs:
 
       - name: Log in to Gitea Container Registry
         shell: sh
+        env:
+          REGISTRY_USERNAME: ${{ secrets.GITEA_REGISTRY_USERNAME }}
+          REGISTRY_TOKEN: ${{ secrets.GITEA_REGISTRY_TOKEN }}
+          LEGACY_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          ACTOR_USERNAME: ${{ github.actor }}
         run: |
-          echo "${{ secrets.GITEA_TOKEN }}" | docker login "${{ steps.meta.outputs.registry_host }}" -u "${{ github.actor }}" --password-stdin
+          USERNAME="$REGISTRY_USERNAME"
+          TOKEN="$REGISTRY_TOKEN"
+
+          if [ -z "$USERNAME" ]; then
+            USERNAME="$ACTOR_USERNAME"
+          fi
+
+          if [ -z "$TOKEN" ]; then
+            TOKEN="$LEGACY_TOKEN"
+          fi
+
+          if [ -z "$USERNAME" ] || [ -z "$TOKEN" ]; then
+            echo "Registry login failed: set GITEA_REGISTRY_USERNAME and GITEA_REGISTRY_TOKEN (or fallback GITEA_TOKEN)."
+            exit 1
+          fi
+
+          echo "$TOKEN" | docker login "${{ steps.meta.outputs.registry_host }}" -u "$USERNAME" --password-stdin
 
       - name: Build and push image
         shell: sh