fix: migrate resourceLocator validation to schema-driven approach (#304, #306)

- Replace hardcoded ['list', 'id', 'url'] modes with schema-based validation
- Read allowed modes from prop.typeOptions.resourceLocator.modes
- Support both object and array mode definition formats
- Add Google Sheets range/columns flexibility for v4+ nodes
- Implement Set node JSON structure validation
- Update tests to verify schema-based validation

Fixes #304 (Google Sheets "name" mode false positive)
Fixes #306 (Set node validation gaps)

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

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

src/services/enhanced-config-validator.ts

@@ -318,7 +318,11 @@ export class EnhancedConfigValidator extends ConfigValidator {
       case 'nodes-base.mysql':
         NodeSpecificValidators.validateMySQL(context);
         break;
-        
+
+      case 'nodes-base.set':
+        NodeSpecificValidators.validateSet(context);
+        break;
+
       case 'nodes-base.switch':
         this.validateSwitchNodeStructure(config, result);
         break;