docs: add INTERNAL_FILES_URL to Docker configuration

- Add INTERNAL_FILES_URL to docker-compose.yaml environment variables
- Add configuration example and documentation to docker/.env.example
- Addresses reviewer feedback for Docker compose file updates

docker/.env.example

@@ -47,6 +47,11 @@ APP_WEB_URL=
 #   ensuring port 5001 is externally accessible (see docker-compose.yaml).
 FILES_URL=
 
+# INTERNAL_FILES_URL is used for plugin daemon communication within Docker network.
+# Set this to the internal Docker service URL for proper plugin file access.
+# Example: INTERNAL_FILES_URL=http://api:5001
+INTERNAL_FILES_URL=
+
 # ------------------------------
 # Server Configuration
 # ------------------------------

docker/docker-compose.yaml

@@ -11,6 +11,7 @@ x-shared-env: &shared-api-worker-env
   APP_API_URL: ${APP_API_URL:-}
   APP_WEB_URL: ${APP_WEB_URL:-}
   FILES_URL: ${FILES_URL:-}
+  INTERNAL_FILES_URL: ${INTERNAL_FILES_URL:-}
   LOG_LEVEL: ${LOG_LEVEL:-INFO}
   LOG_FILE: ${LOG_FILE:-/app/logs/server.log}
   LOG_FILE_MAX_SIZE: ${LOG_FILE_MAX_SIZE:-20}