feat: move n8n to dev stack under n8n.dev.pivoine.art

- Moved n8n service from standalone stack to dev/compose.yaml
- Updated hostname from n8n.pivoine.art to n8n.dev.pivoine.art
- Updated environment variables to use DEV_N8N_ prefix
- Updated restic backup volume reference (n8n_n8n_data -> dev_n8n_data)
- Removed standalone n8n/compose.yaml
- Container name changes from n8n_app to dev_n8n
- Volume name changes from n8n_n8n_data to dev_n8n_data

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

arty.yml

@@ -59,14 +59,6 @@ envs:
     TANDOOR_GUNICORN_MEDIA: 0
     TANDOOR_COMMENT_PREF_DEFAULT: 1
     TANDOOR_SHOPPING_MIN_AUTOSYNC_INTERVAL: 5
-    # n8n
-    N8N_TRAEFIK_ENABLED: true
-    N8N_COMPOSE_PROJECT_NAME: n8n
-    N8N_IMAGE: docker.n8n.io/n8nio/n8n
-    N8N_TRAEFIK_HOST: n8n.pivoine.art
-    N8N_PORT: 5678
-    N8N_DB_NAME: n8n
-    N8N_DB_SCHEMA: public
     # Filestash
     STASH_TRAEFIK_ENABLED: true
     STASH_COMPOSE_PROJECT_NAME: stash
@@ -128,6 +120,10 @@ envs:
     DEV_COOLIFY_IMAGE: ghcr.io/coollabsio/coolify:latest
     DEV_COOLIFY_TRAEFIK_HOST: coolify.dev.pivoine.art
     DEV_COOLIFY_DB_NAME: coolify
+    DEV_N8N_IMAGE: docker.n8n.io/n8nio/n8n
+    DEV_N8N_TRAEFIK_HOST: n8n.dev.pivoine.art
+    DEV_N8N_DB_NAME: n8n
+    DEV_N8N_DB_SCHEMA: public
     # PairDrop
     DROP_TRAEFIK_ENABLED: true
     DROP_COMPOSE_PROJECT_NAME: drop