Add webhook subscription MCP tools and N8N operations

Expose webhook subscription CRUD and event listing through the MCP API
(list, get, create, update, delete subscriptions + list events) and add
a new webhook resource to the N8N node with matching operations.

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

packages/n8n-node/nodes/Probo/Probo.node.ts

@@ -146,6 +146,11 @@ export class Probo implements INodeType {
 						value: 'vendor',
 						description: 'Manage vendors',
 					},
+					{
+						name: 'Webhook',
+						value: 'webhook',
+						description: 'Manage webhook subscriptions',
+					},
 				],
 				default: 'execute',
 			},