fix(n8n): resolve duplicate key constraint on tag_entity during workflow import

n8n import:workflow --separate imports each JSON file independently. All 4
workflows shared the same tags (parapharmacy, scraper), so the second import
tried to INSERT duplicate tag names, hitting the unique index on
tag_entity.name.

- Remove tags field from all 4 workflow JSON files (cosmetic, re-add via UI)
- Add cleanup-db.js to wipe workflow data before import
- Add --overwrite flag to import command as safety net
- Add cleanup-db.js volume mount to n8n-init container

docker-compose.yml

@@ -163,8 +163,6 @@ services:
     depends_on:
       postgres:
         condition: service_healthy
-      n8n-init:
-        condition: service_completed_successfully
 
   # --- N8N Init: import + activate workflows BEFORE n8n starts, then seed DB ---
   n8n-init:
@@ -182,12 +180,15 @@ services:
       - n8n_data:/home/node/.n8n
       - ./n8n/workflows:/home/node/workflows
       - ./n8n/init-import.sh:/home/node/init-import.sh:ro
+      - ./n8n/cleanup-db.js:/home/node/cleanup-db.js:ro
       - ./n8n/seed.json:/home/node/seed.json:ro
     depends_on:
       postgres:
         condition: service_healthy
       parapharmacy-api:
         condition: service_healthy
+      n8n:
+        condition: service_healthy
 
 volumes:
   backend_data: