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/mcp/tools-n8n-manager.ts

@@ -63,6 +63,10 @@ export const n8nManagementTools: ToolDefinition[] = [
             executionTimeout: { type: 'number' },
             errorWorkflow: { type: 'string' }
           }
+        },
+        projectId: {
+          type: 'string',
+          description: 'Optional project ID to create the workflow in (enterprise feature)'
         }
       },
       required: ['name', 'nodes', 'connections']
@@ -602,5 +606,38 @@ export const n8nManagementTools: ToolDefinition[] = [
       destructiveHint: false,
       openWorldHint: true,
     },
-  }
+  },
+  {
+    name: 'n8n_create_data_table',
+    description: 'Create a new data table in n8n. Requires n8n enterprise or cloud with data tables feature.',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        name: { type: 'string', description: 'Name for the data table' },
+        columns: {
+          type: 'array',
+          description: 'Column definitions',
+          items: {
+            type: 'object',
+            properties: {
+              name: { type: 'string', description: 'Column name' },
+              type: {
+                type: 'string',
+                enum: ['string', 'number', 'boolean', 'date', 'json'],
+                description: 'Column data type',
+              },
+            },
+            required: ['name'],
+          },
+        },
+      },
+      required: ['name'],
+    },
+    annotations: {
+      title: 'Create Data Table',
+      readOnlyHint: false,
+      destructiveHint: false,
+      openWorldHint: true,
+    },
+  },
 ];