fix: update GHCR image name to use dynamic repository path

Author: Slach

.github/workflows/build-gateway.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   REGISTRY: ghcr.io
-  IMAGE_NAME: altinity/altinity-mcp/gateway
+  IMAGE_NAME: ${{ github.repository }}/gateway
 
 jobs:
   build: