feat: add n8n_create_data_table MCP tool and projectId for create workflow (#640)

Add new MCP tool to create n8n data tables via the REST API:
- n8n_create_data_table tool definition with name + columns schema
- handleCreateDataTable handler with Zod validation and N8nApiError handling
- N8nApiClient.createDataTable() calling POST /data-tables
- DataTable, DataTableColumn, DataTableColumnResponse types per OpenAPI spec
- Column types: string | number | boolean | date | json
- Input validation: .min(1) on table name and column names
- Tool documentation with examples, use cases, and pitfalls

Also adds projectId parameter to n8n_create_workflow for enterprise
project support, and fixes stale management tool count in health check.

Based on work by @djakielski in PR #646.
Co-Authored-By: Dominik Jakielski <dominik.jakielski@urlaubsguru.de>

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

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

src/services/n8n-api-client.ts

@@ -22,6 +22,8 @@ import {
   SourceControlStatus,
   SourceControlPullResult,
   SourceControlPushResult,
+  DataTable,
+  DataTableColumn,
 } from '../types/n8n-api';
 import { handleN8nApiError, logN8nError } from '../utils/n8n-errors';
 import { cleanWorkflowForCreate, cleanWorkflowForUpdate } from './n8n-validation';
@@ -582,6 +584,15 @@ export class N8nApiClient {
     }
   }
 
+  async createDataTable(params: { name: string; columns?: DataTableColumn[] }): Promise<DataTable> {
+    try {
+      const response = await this.client.post('/data-tables', params);
+      return response.data;
+    } catch (error) {
+      throw handleN8nApiError(error);
+    }
+  }
+
   /**
    * Validates and normalizes n8n API list responses.
    * Handles both modern format {data: [], nextCursor?: string} and legacy array format.