feat: add template metadata generation and smart discovery

- Implement OpenAI batch API integration for metadata generation
- Add search_templates_by_metadata tool with advanced filtering
- Enhance list_templates to include descriptions and optional metadata
- Generate metadata for 2,534 templates (97.5% coverage)
- Update README with Template Tools section and enhanced Claude setup
- Add comprehensive documentation for metadata system

Enables intelligent template discovery through:
- Complexity levels (simple/medium/complex)
- Setup time estimates (5-480 minutes)
- Target audience filtering (developers/marketers/analysts)
- Required services detection
- Category and use case classification

Co-Authored-By: Claude <noreply@anthropic.com>

src/mcp/tool-docs/index.ts

@@ -22,7 +22,8 @@ import {
   getNodeForTaskDoc, 
   listNodeTemplatesDoc, 
   getTemplateDoc, 
-  searchTemplatesDoc, 
+  searchTemplatesDoc,
+  searchTemplatesByMetadataDoc, 
   getTemplatesForTaskDoc 
 } from './templates';
 import { 
@@ -83,6 +84,7 @@ export const toolsDocumentation: Record<string, ToolDocumentation> = {
   list_node_templates: listNodeTemplatesDoc,
   get_template: getTemplateDoc,
   search_templates: searchTemplatesDoc,
+  search_templates_by_metadata: searchTemplatesByMetadataDoc,
   get_templates_for_task: getTemplatesForTaskDoc,
   
   // Workflow Management tools (n8n API)