feat: add _cnd conditional operator support and n8n 2.0+ executeWorkflowTrigger fix

Added:
- Support for all 12 _cnd operators in displayOptions validation (eq, not, gte, lte, gt, lt, between, startsWith, endsWith, includes, regex, exists)
- Version-based visibility checking with @version in config
- 42 new unit tests for _cnd operators

Fixed:
- n8n 2.0+ breaking change: executeWorkflowTrigger now recognized as activatable trigger
- Removed outdated validation blocking Execute Workflow Trigger workflows

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

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

dist/services/workflow-validator.js

@@ -310,7 +310,11 @@ class WorkflowValidator {
                 if (normalizedType.startsWith('nodes-langchain.')) {
                     continue;
                 }
-                const nodeValidation = this.nodeValidator.validateWithMode(node.type, node.parameters, nodeInfo.properties || [], 'operation', profile);
+                const paramsWithVersion = {
+                    '@version': node.typeVersion || 1,
+                    ...node.parameters
+                };
+                const nodeValidation = this.nodeValidator.validateWithMode(node.type, paramsWithVersion, nodeInfo.properties || [], 'operation', profile);
                 nodeValidation.errors.forEach((error) => {
                     result.errors.push({
                         type: 'error',