fix: resolve TypeScript compilation errors in integration tests

Fixed multiple TypeScript errors preventing clean build:
- Fixed import paths for ValidationResponse type (5 test files)
- Fixed validateBasicLLMChain function signature (removed extra workflow parameter)
- Enhanced ValidationResponse interface to include missing properties:
  - Added code, nodeName fields to errors/warnings
  - Added info array for informational messages
  - Added suggestions array
- Fixed type assertion in mergeConnections helper
- Fixed implicit any type in chat-trigger-validation test

All tests now compile cleanly with no TypeScript errors.

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

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

tests/unit/services/ai-node-validator.test.ts

@@ -586,7 +586,7 @@ describe('AI Node Validator', () => {
       };
 
       const reverseMap = buildReverseConnectionMap(workflow);
-      const issues = validateBasicLLMChain(chain, reverseMap, workflow);
+      const issues = validateBasicLLMChain(chain, reverseMap);
 
       expect(issues).toContainEqual(
         expect.objectContaining({
@@ -617,7 +617,7 @@ describe('AI Node Validator', () => {
       };
 
       const reverseMap = buildReverseConnectionMap(workflow);
-      const issues = validateBasicLLMChain(chain, reverseMap, workflow);
+      const issues = validateBasicLLMChain(chain, reverseMap);
 
       const errors = issues.filter(i => i.severity === 'error');
       expect(errors).toHaveLength(0);