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

n8n/init-import.sh

@@ -11,9 +11,13 @@ if [ -f "$FLAG" ]; then
   exit 0
 fi
 
+# ── 0. Clean existing workflow data to avoid constraint violations ────
+echo "[n8n-init] Cleaning existing workflow data..."
+node /home/node/cleanup-db.js 2>&1 || echo "[n8n-init] Cleanup skipped (first run or no existing data)."
+
 # ── 1. Import workflows via CLI (writes to DB) ───────────────────────
 echo "[n8n-init] Importing workflows..."
-n8n import:workflow --separate --input=/home/node/workflows/ 2>/dev/null
+n8n import:workflow --separate --overwrite --input=/home/node/workflows/ 2>/dev/null
 
 # ── 3. Activate all workflows via CLI ────────────────────────────────
 echo "[n8n-init] Activating workflows..."