Fix group attribute syntax: use correct [group('name')] format

- Change all [group: 'name'] to [group('name')] per Just documentation
- Ensures compatibility with Just 1.21.0 and resolves 'Unknown attribute group' error
- Affects all just-commons files: container, volumes, postgres, mysql, images, registry, core

images.just

@@ -1,7 +1,7 @@
 # Universal image operations - works for any project
 
 # Build any project's container image
-[group: 'images']
+[group('images')]
 image-build project *args="":
     #!/usr/bin/env bash
     set -euo pipefail
@@ -58,7 +58,7 @@ image-build project *args="":
     echo -e "${GREEN}✓ Local tags: $project:$tag, $project:latest${NC}"
 
 # Push any project's image to registry
-[group: 'images']
+[group('images')]
 image-push project tag=DEFAULT_TAG:
     #!/usr/bin/env bash
     set -euo pipefail
@@ -133,7 +133,7 @@ image-push project tag=DEFAULT_TAG:
     fi
 
 # Pull any project's image from registry
-[group: 'images']
+[group('images')]
 image-pull project tag=DEFAULT_TAG:
     #!/usr/bin/env bash
     set -euo pipefail
@@ -286,7 +286,7 @@ image-info project tag="latest":
     fi
 
 # List all project images
-[group: 'images']
+[group('images')]
 images-list:
     #!/usr/bin/env bash
     set -euo pipefail