fix: correct misleading Code node documentation based on real-world testing

Critical fixes based on Claude Desktop feedback:

1. Fixed crypto documentation: require('crypto') IS available despite editor warnings
   - Added clear examples of crypto usage
   - Updated validation to guide correct require() usage

2. Clarified $helpers vs standalone functions
   - $getWorkflowStaticData() is standalone, NOT $helpers.getWorkflowStaticData()
   - Added validation to catch incorrect usage (prevents '$helpers is not defined' errors)
   - Enhanced examples showing proper $helpers availability checks

3. Fixed JMESPath numeric literal documentation
   - n8n requires backticks around numbers in filters: [?age >= `18`]
   - Added multiple examples and validation to detect missing backticks
   - Prevents 'JMESPath syntax error' that Claude Desktop encountered

4. Fixed webhook data access gotcha
   - Webhook payload is at items[0].json.body, NOT items[0].json
   - Added dedicated 'Webhook Data Access' section with clear examples
   - Created process_webhook_data task template
   - Added validation to detect incorrect webhook data access patterns

All fixes based on production workflows TaNqYoZNNeHC4Hne and JZ9urD7PNClDZ1bm

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/services/enhanced-config-validator.ts

@@ -213,7 +213,7 @@ export class EnhancedConfigValidator extends ConfigValidator {
         break;
         
       case 'nodes-base.code':
-        // Code node uses base validation which includes syntax checks
+        NodeSpecificValidators.validateCode(context);
         break;
         
       case 'nodes-base.openAi':