fix: install npm packages in task runner for code node support

n8n v2.0 executes code nodes in a separate task runner container.
the runner image (n8nio/runners) doesn't include npm packages like
cheerio, axios, moment, lodash - causing "module is disallowed" errors.

- add Dockerfile.runner with npm packages for code nodes
- rename Dockerfile to Dockerfile.n8n for clarity
- update docker-compose.yml to use custom runner build

docker-compose.yml

@@ -37,6 +37,7 @@ volumes:
 x-n8n: &service-n8n
   build:
     context: ./n8n
+    dockerfile: Dockerfile.n8n
     pull: true
     args:
       N8N_VERSION: ${N8N_VERSION:-stable}
@@ -111,7 +112,12 @@ x-init-ollama: &init-ollama
 
 # Worker-runner anchor for sidecar pattern (runner connects to worker via localhost)
 x-n8n-worker-runner: &service-n8n-worker-runner
-  image: n8nio/runners:${N8N_VERSION:-stable}
+  build:
+    context: ./n8n
+    dockerfile: Dockerfile.runner
+    pull: true
+    args:
+      N8N_VERSION: ${N8N_VERSION:-stable}
   environment:
     N8N_RUNNERS_AUTH_TOKEN: ${N8N_RUNNERS_AUTH_TOKEN}
     N8N_RUNNERS_AUTO_SHUTDOWN_TIMEOUT: 15

n8n/Dockerfile.runner

@@ -0,0 +1,10 @@
+ARG N8N_VERSION=stable
+FROM n8nio/runners:${N8N_VERSION}
+
+USER root
+
+# Install npm packages that can be used in Code nodes
+# These must match NODE_FUNCTION_ALLOW_EXTERNAL in docker-compose.yml
+RUN npm install -g cheerio axios moment lodash
+
+USER node