feat: add n8n_generate_workflow tool for hosted workflow generation

Add new MCP tool that enables AI-powered workflow generation from natural
language descriptions. Uses handler delegation pattern — hosting environments
inject a GenerateWorkflowHandler via EngineOptions, self-hosted instances
receive a hosted-only informational response.

Handler flows through N8NMCPEngine → SingleSessionHTTPServer →
N8NDocumentationMCPServer with helpers for createWorkflow, validateWorkflow,
autofixWorkflow, and getWorkflow.

Includes full tool documentation, tests, and corrected tools overview count.

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/mcp/tool-docs/index.ts

@@ -23,7 +23,8 @@ import {
   n8nExecutionsDoc,
   n8nWorkflowVersionsDoc,
   n8nDeployTemplateDoc,
-  n8nManageDatatableDoc
+  n8nManageDatatableDoc,
+  n8nGenerateWorkflowDoc
 } from './workflow_management';
 
 // Combine all tool documentations into a single object
@@ -62,7 +63,8 @@ export const toolsDocumentation: Record<string, ToolDocumentation> = {
   n8n_executions: n8nExecutionsDoc,
   n8n_workflow_versions: n8nWorkflowVersionsDoc,
   n8n_deploy_template: n8nDeployTemplateDoc,
-  n8n_manage_datatable: n8nManageDatatableDoc
+  n8n_manage_datatable: n8nManageDatatableDoc,
+  n8n_generate_workflow: n8nGenerateWorkflowDoc
 };
 
 // Re-export types