Add N8n integration with models, services, and routes

- Introduced N8n and N8nSetting models in both MySQL and PostgreSQL schemas.
- Implemented N8nController and N8nService for managing N8n bots.
- Created N8nRouter for handling API requests related to N8n.
- Added DTOs and validation schemas for N8n integration.
- Updated server module and chatbot controller to include N8n functionality.
- Configured environment settings for N8n integration.

src/api/integrations/chatbot/n8n/dto/n8n.dto.ts

@@ -0,0 +1,34 @@
+import { TriggerType, TriggerOperator } from '@prisma/client';
+
+export class N8nDto {
+  enabled?: boolean;
+  description?: string;
+  webhookUrl?: string;
+  basicAuthUser?: string;
+  basicAuthPass?: string;
+
+  // Advanced bot properties (copied from DifyDto style)
+  triggerType?: TriggerType;
+  triggerOperator?: TriggerOperator;
+  triggerValue?: string;
+  expire?: number;
+  keywordFinish?: string;
+  delayMessage?: number;
+  unknownMessage?: string;
+  listeningFromMe?: boolean;
+  stopBotFromMe?: boolean;
+  keepOpen?: boolean;
+  debounceTime?: number;
+  ignoreJids?: string[];
+  splitMessages?: boolean;
+  timePerChar?: number;
+}
+
+export class N8nSettingDto {
+  // Add settings fields here if needed for compatibility
+}
+
+export class N8nMessageDto {
+  chatInput: string;
+  sessionId: string;
+}