fix: recognize dynamic AI Tool nodes in validator (Issue #522) (#526)

When n8n connects any node to an AI Agent's tool slot, it creates a
dynamic Tool variant at runtime (e.g., googleDrive → googleDriveTool).
These don't exist in npm packages, causing false "unknown node type"
errors.

Added validation-time inference: when a *Tool node type is not found,
check if the base node exists. If yes, treat as valid with warning.

Changes:
- workflow-validator.ts: Add INFERRED_TOOL_VARIANT logic
- node-similarity-service.ts: Add 98% confidence for valid Tool variants
- Added 7 unit tests for inferred tool variant functionality

Fixes #522

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

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

Co-authored-by: Romuald Członkowski <romualdczlonkowski@MacBook-Pro-Romuald.local>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/services/node-similarity-service.ts

@@ -1,5 +1,6 @@
 import { NodeRepository } from '../database/node-repository';
 import { logger } from '../utils/logger';
+import { ToolVariantGenerator } from './tool-variant-generator';
 
 export interface NodeSuggestion {
   nodeType: string;
@@ -126,6 +127,25 @@ export class NodeSimilarityService {
       return [];
     }
 
+    // Check if this is a Tool variant and base node exists (Issue #522)
+    // Dynamic AI Tool variants like googleDriveTool are created at runtime by n8n
+    if (ToolVariantGenerator.isToolVariantNodeType(invalidType)) {
+      const baseNodeType = ToolVariantGenerator.getBaseNodeType(invalidType);
+      if (baseNodeType) {
+        const baseNode = this.repository.getNode(baseNodeType);
+        if (baseNode) {
+          return [{
+            nodeType: invalidType,
+            displayName: `${baseNode.displayName} Tool`,
+            confidence: 0.98,
+            reason: `Dynamic AI Tool variant of ${baseNode.displayName}`,
+            category: baseNode.category,
+            description: 'Runtime-generated Tool variant for AI Agent integration'
+          }];
+        }
+      }
+    }
+
     const suggestions: NodeSuggestion[] = [];
 
     // First, check for exact common mistakes