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/types/n8n-api.ts

@@ -454,4 +454,26 @@ export interface ErrorSuggestion {
   title: string;
   description: string;
   confidence: 'high' | 'medium' | 'low';
+}
+
+// Data Table types
+export interface DataTableColumn {
+  name: string;
+  type?: 'string' | 'number' | 'boolean' | 'date' | 'json';
+}
+
+export interface DataTableColumnResponse {
+  id: string;
+  name: string;
+  type: 'string' | 'number' | 'boolean' | 'date' | 'json';
+  index: number;
+}
+
+export interface DataTable {
+  id: string;
+  name: string;
+  columns?: DataTableColumnResponse[];
+  projectId?: string;
+  createdAt?: string;
+  updatedAt?: string;
 }