fix: recognize all trigger node types including executeWorkflowTrigger (#351) (#352)

This fix addresses issue #351 where Execute Workflow Trigger and other
trigger nodes were incorrectly treated as regular nodes, causing
"disconnected node" errors during partial workflow updates.

## Changes

**1. Created Shared Trigger Detection Utilities**
- src/utils/node-type-utils.ts:
  - isTriggerNode(): Recognizes ALL trigger types using flexible pattern matching
  - isActivatableTrigger(): Returns false for executeWorkflowTrigger (not activatable)
  - getTriggerTypeDescription(): Human-readable trigger descriptions

**2. Updated Workflow Validation**
- src/services/n8n-validation.ts:
  - Replaced hardcoded webhookTypes Set with isTriggerNode() function
  - Added validation preventing activation of workflows with only executeWorkflowTrigger
  - Now recognizes 200+ trigger types across n8n packages

**3. Updated Workflow Validator**
- src/services/workflow-validator.ts:
  - Replaced inline trigger detection with shared isTriggerNode() function
  - Ensures consistency across all validation code paths

**4. Comprehensive Tests**
- tests/unit/utils/node-type-utils.test.ts:
  - Added 30+ tests for trigger detection functions
  - Validates all trigger types are recognized correctly
  - Confirms executeWorkflowTrigger is trigger but not activatable

## Impact

Before:
- Execute Workflow Trigger flagged as disconnected node
- Schedule/email/polling triggers also rejected
- Users forced to keep unnecessary webhook triggers

After:
- ALL trigger types recognized (executeWorkflowTrigger, scheduleTrigger, etc.)
- No disconnected node errors for triggers
- Clear error when activating workflow with only executeWorkflowTrigger
- Future-proof (new triggers automatically supported)

## Testing

- Build: ✅ Passes
- Typecheck: ✅ Passes
- Unit tests: ✅ All pass
- Validation test: ✅ Trigger detection working correctly

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

src/services/workflow-validator.ts

@@ -11,6 +11,7 @@ import { NodeSimilarityService, NodeSuggestion } from './node-similarity-service
 import { NodeTypeNormalizer } from '../utils/node-type-normalizer';
 import { Logger } from '../utils/logger';
 import { validateAISpecificNodes, hasAINodes } from './ai-node-validator';
+import { isTriggerNode } from '../utils/node-type-utils';
 import { isNonExecutableNode } from '../utils/node-classification';
 const logger = new Logger({ prefix: '[WorkflowValidator]' });
 
@@ -318,16 +319,8 @@ export class WorkflowValidator {
       nodeIds.add(node.id);
     }
 
-    // Count trigger nodes - normalize type names first
-    const triggerNodes = workflow.nodes.filter(n => {
-      const normalizedType = NodeTypeNormalizer.normalizeToFullForm(n.type);
-      const lowerType = normalizedType.toLowerCase();
-      return lowerType.includes('trigger') ||
-             (lowerType.includes('webhook') && !lowerType.includes('respond')) ||
-             normalizedType === 'nodes-base.start' ||
-             normalizedType === 'nodes-base.manualTrigger' ||
-             normalizedType === 'nodes-base.formTrigger';
-    });
+    // Count trigger nodes using shared trigger detection
+    const triggerNodes = workflow.nodes.filter(n => isTriggerNode(n.type));
     result.statistics.triggerNodes = triggerNodes.length;
 
     // Check for at least one trigger node
@@ -626,14 +619,10 @@ export class WorkflowValidator {
     for (const node of workflow.nodes) {
       if (node.disabled || isNonExecutableNode(node.type)) continue;
 
-      const normalizedType = NodeTypeNormalizer.normalizeToFullForm(node.type);
-      const isTrigger = normalizedType.toLowerCase().includes('trigger') ||
-                       normalizedType.toLowerCase().includes('webhook') ||
-                       normalizedType === 'nodes-base.start' ||
-                       normalizedType === 'nodes-base.manualTrigger' ||
-                       normalizedType === 'nodes-base.formTrigger';
-      
-      if (!connectedNodes.has(node.name) && !isTrigger) {
+      // Use shared trigger detection function for consistency
+      const isNodeTrigger = isTriggerNode(node.type);
+
+      if (!connectedNodes.has(node.name) && !isNodeTrigger) {
         result.warnings.push({
           type: 'warning',
           nodeId: node.id,