feat: Add detailed logging for description endpoint and n8n workflow docs

Added:
- Detailed logging for /api/v1/claims/description endpoint
- Full event data logging for debugging
- Documentation for n8n workflow setup (N8N_DESCRIPTION_WORKFLOW.md)

The issue: Form hangs on recommendations step because n8n doesn't process description events.

Flow:
1. Frontend sends description to /api/v1/claims/description
2. Backend publishes to Redis channel ticket_form:description
3. Frontend subscribes to SSE /api/v1/events/{session_id} (listens to ocr_events:{session_id})
4. n8n must:
   - Subscribe to ticket_form:description channel
   - Process description and generate wizard_plan
   - Publish wizard_plan back to ocr_events:{session_id} channel

Files:
- backend/app/api/claims.py (enhanced logging)
- docs/N8N_DESCRIPTION_WORKFLOW.md (new documentation)

backend/app/api/claims.py

@@ -692,14 +692,49 @@ async def publish_ticket_form_description(payload: TicketFormDescriptionRequest)
             "source": payload.source,
             "timestamp": datetime.utcnow().isoformat(),
         }
+        
+        event_json = json.dumps(event, ensure_ascii=False)
+        
         logger.info(
             "📝 TicketForm description received",
-            extra={"session_id": payload.session_id, "claim_id": payload.claim_id or "not_set"},
+            extra={
+                "session_id": payload.session_id,
+                "claim_id": payload.claim_id or "not_set",
+                "phone": payload.phone,
+                "description_length": len(payload.problem_description),
+                "channel": channel,
+            },
         )
-        await redis_service.publish(channel, json.dumps(event, ensure_ascii=False))
+        
         logger.info(
-            "📡 TicketForm description published",
-            extra={"channel": channel, "session_id": payload.session_id},
+            "📡 Publishing to Redis channel",
+            extra={
+                "channel": channel,
+                "event_type": event["type"],
+                "event_keys": list(event.keys()),
+                "json_length": len(event_json),
+            },
+        )
+        
+        await redis_service.publish(channel, event_json)
+        
+        logger.info(
+            "✅ TicketForm description published to Redis",
+            extra={
+                "channel": channel,
+                "session_id": payload.session_id,
+                "subscribers_notified": True,
+                "event_json_preview": event_json[:500],
+            },
+        )
+        
+        # Дополнительная проверка: логируем полный event для отладки
+        logger.debug(
+            "🔍 Full event data published",
+            extra={
+                "channel": channel,
+                "event": event,
+            },
         )
         return {
             "success": True,