refactor: remove 6 chatbot integrations keeping only N8N

Removed chatbot integrations: Chatwoot, Typebot, OpenAI, Dify, Flowise, and EvoAI.
Only N8N integration remains active.

Changes include:
- Deleted all integration directories and files (controllers, services, DTOs, validators, routers)
- Updated chatbot.controller.ts to only emit to N8N
- Updated chatbot.router.ts and chatbot.schema.ts to export only N8N
- Removed OpenAI dependency from N8nService (removed audio transcription)
- Updated server.module.ts to remove all chatbot service instantiations
- Cleaned monitor.service.ts and channel.service.ts from chatbot references
- Removed chatbot properties from DTOs and validation schemas
- Removed LocalChatwoot type and TYPEBOT events from wa.types
- Cleaned PostgreSQL Prisma schema: removed 12 models and 2 enums
- Removed chatbot relations from Instance model
- Removed Chatwoot fields from Message model

N8N remains as the only supported chatbot integration.

prisma/mysql-schema.prisma

@@ -48,18 +48,6 @@ enum TriggerOperator {
   regex
 }
 
-enum OpenaiBotType {
-  assistant
-  chatCompletion
-}
-
-enum DifyBotType {
-  chatBot
-  textGenerator
-  agent
-  workflow
-}
-
 model Instance {
   id                      String                   @id @default(cuid())
   name                    String                   @unique @db.VarChar(255)