fix: Chatbot-Workflows korrigiert und Memory-Bug behoben

- Inline SQL-Expressions statt queryParams (Postgres-Node-Kompatibilität)
- CTE-Query garantiert immer eine Zeile (verhindert Abbruch bei neuer Session)
- Delete-Workflow ebenfalls auf inline SQL umgestellt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

imports/workflows/ollama-chat-delete.json

@@ -19,10 +19,8 @@
     {
       "parameters": {
         "operation": "executeQuery",
-        "query": "DELETE FROM chat_sessions WHERE session_id = $1 RETURNING session_id",
-        "additionalFields": {
-          "queryParams": "={{ JSON.stringify([$json.body.session_id]) }}"
-        }
+        "query": "=DELETE FROM chat_sessions WHERE session_id = '{{ $json.body.session_id }}' RETURNING session_id",
+        "additionalFields": {}
       },
       "id": "node-pg-004",
       "name": "Delete Session",
@@ -31,8 +29,8 @@
       "position": [300, 300],
       "credentials": {
         "postgres": {
-          "id": "SETUP_REQUIRED",
-          "name": "n8n PostgreSQL"
+          "id": "pnmeNZ3ONDWrQP8M",
+          "name": "Postgres account"
         }
       }
     },