feat: implement Phase 2 validation improvements

Phase 2 Professional Validation Features:

1. Validation Profiles:
   - minimal: Only required fields
   - runtime: Critical errors + security warnings
   - ai-friendly: Balanced (default)
   - strict: All checks + best practices

2. New Node Validators:
   - Webhook: Path validation, response modes, auth warnings
   - PostgreSQL: SQL injection detection, query safety
   - MySQL: Similar to Postgres with MySQL-specific checks

3. New Tools:
   - validate_node_minimal: Lightning-fast required field checking
   - Updated validate_node_operation with profile support

4. SQL Safety Features:
   - Detects template expressions vulnerable to injection
   - Warns about DELETE/UPDATE without WHERE
   - Catches dangerous operations (DROP, TRUNCATE)
   - Suggests parameterized queries

5. Enhanced Coverage:
   - Now supports 7+ major nodes with specific validators
   - Flexible validation based on use case
   - Professional-grade safety checks

This completes the major validation system overhaul from the original plan.

🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>

src/services/config-validator.ts

@@ -304,28 +304,7 @@ export class ConfigValidator {
     warnings: ValidationWarning[],
     suggestions: string[]
   ): void {
-    // Path validation
-    if (config.path) {
-      if (config.path.startsWith('/')) {
-        warnings.push({
-          type: 'inefficient',
-          property: 'path',
-          message: 'Webhook path should not start with /',
-          suggestion: 'Remove the leading / from the path'
-        });
-      }
-      
-      if (config.path.includes(' ')) {
-        warnings.push({
-          type: 'inefficient',
-          property: 'path',
-          message: 'Webhook path contains spaces',
-          suggestion: 'Use hyphens or underscores instead of spaces'
-        });
-      }
-    }
-    
-    // Response mode suggestions
+    // Basic webhook validation - moved detailed validation to NodeSpecificValidators
     if (config.responseMode === 'responseNode' && !config.responseData) {
       suggestions.push('When using responseMode=responseNode, add a "Respond to Webhook" node to send custom responses');
     }