fix: use bind mount with HOST_DATA_DIR in docker-compose.yml (closes #120)

Replace named volume with bind mount so the host path is known and passed
via UPAAS_HOST_DATA_DIR. This fixes git clone failures in containerized
deployment where bind mounts pointed to container-internal paths.

docker-compose.yml

@@ -6,8 +6,9 @@ services:
       - "8080:8080"
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
-      - upaas-data:/var/lib/upaas
-    # environment:
+      - ${HOST_DATA_DIR:-./data}:/var/lib/upaas
+    environment:
+      - UPAAS_HOST_DATA_DIR=${HOST_DATA_DIR:-./data}
       # Optional: uncomment to enable debug logging
       # - DEBUG=true
       # Optional: Sentry error reporting
@@ -15,6 +16,3 @@ services:
       # Optional: Prometheus metrics auth
       # - METRICS_USERNAME=prometheus
       # - METRICS_PASSWORD=secret
-
-volumes:
-  upaas-data: