feat: add workflowNodeType field to MCP tool responses for proper n8n workflow creation

- Added workflowNodeType field to all node-returning MCP tools
- AI agents now receive both internal format (nodes-base.webhook) and workflow format (n8n-nodes-base.webhook)
- Created getWorkflowNodeType() utility to construct proper n8n format from package name
- Solves issue where AI agents would search nodes and use wrong format in workflows
- No database changes required - uses existing package_name field
- Updated: search_nodes, get_node_info, get_node_essentials, get_node_as_tool_info, validate_node_operation
- Updated CHANGELOG.md with comprehensive documentation of the changes

This completes the fix for issue #71, ensuring AI agents can seamlessly create workflows
with the correct node type format without manual intervention.

src/utils/node-utils.ts

@@ -43,4 +43,31 @@ export function getNodeTypeAlternatives(nodeType: string): string[] {
   }
   
   return alternatives;
+}
+
+/**
+ * Constructs the workflow node type from package name and normalized node type
+ * This creates the format that n8n expects in workflow definitions
+ * 
+ * Examples:
+ * - ('n8n-nodes-base', 'nodes-base.webhook') → 'n8n-nodes-base.webhook'
+ * - ('@n8n/n8n-nodes-langchain', 'nodes-langchain.agent') → '@n8n/n8n-nodes-langchain.agent'
+ * 
+ * @param packageName The package name from the database
+ * @param nodeType The normalized node type from the database
+ * @returns The workflow node type for use in n8n workflows
+ */
+export function getWorkflowNodeType(packageName: string, nodeType: string): string {
+  // Extract just the node name from the normalized type
+  const nodeName = nodeType.split('.').pop() || nodeType;
+  
+  // Construct the full workflow type based on package
+  if (packageName === 'n8n-nodes-base') {
+    return `n8n-nodes-base.${nodeName}`;
+  } else if (packageName === '@n8n/n8n-nodes-langchain') {
+    return `@n8n/n8n-nodes-langchain.${nodeName}`;
+  }
+  
+  // Fallback for unknown packages - return as is
+  return nodeType;
 }