fix: ensure config directory exists

- Create config directory in Dockerfile
- Use explicit volume bind mount syntax
- Fix config.yml mounting issue

Dockerfile

@@ -1,4 +1,7 @@
-FROM registry:2 AS base
+FROM registry:2
 
 # Use Alpine's apk package manager to install apache2-utils
-RUN apk --no-cache add apache2-utils
+RUN apk --no-cache add apache2-utils
+
+# Create config directory
+RUN mkdir -p /etc/docker/registry/