Bind-mount PocketBase data dir in local dev instead of a named volume

Makes local test data (e.g. content pulled from production for testing)
directly inspectable and swappable on the host filesystem, without
affecting the production volume-based setup.

docker-compose.dev.yml

@@ -5,6 +5,8 @@ services:
   pocketbase:
     ports:
       - "127.0.0.1:8090:8090"
+    volumes:
+      - ./pocketbase/pb_data:/pb/pb_data
 
   frontend:
     ports: