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>

dist/services/workflow-validator.js

@@ -236,7 +236,31 @@ class WorkflowValidator {
                     }
                 }
                 const normalizedType = node_type_normalizer_1.NodeTypeNormalizer.normalizeToFullForm(node.type);
-                const nodeInfo = this.nodeRepository.getNode(normalizedType);
+                let nodeInfo = this.nodeRepository.getNode(normalizedType);
+                if (!nodeInfo && tool_variant_generator_1.ToolVariantGenerator.isToolVariantNodeType(normalizedType)) {
+                    const baseNodeType = tool_variant_generator_1.ToolVariantGenerator.getBaseNodeType(normalizedType);
+                    if (baseNodeType) {
+                        const baseNodeInfo = this.nodeRepository.getNode(baseNodeType);
+                        if (baseNodeInfo) {
+                            result.warnings.push({
+                                type: 'warning',
+                                nodeId: node.id,
+                                nodeName: node.name,
+                                message: `Node type "${node.type}" is inferred as a dynamic AI Tool variant of "${baseNodeType}". ` +
+                                    `This Tool variant is created by n8n at runtime when connecting "${baseNodeInfo.displayName}" to an AI Agent.`,
+                                code: 'INFERRED_TOOL_VARIANT'
+                            });
+                            nodeInfo = {
+                                ...baseNodeInfo,
+                                nodeType: normalizedType,
+                                displayName: `${baseNodeInfo.displayName} Tool`,
+                                isToolVariant: true,
+                                toolVariantOf: baseNodeType,
+                                isInferred: true
+                            };
+                        }
+                    }
+                }
                 if (!nodeInfo) {
                     const suggestions = await this.similarityService.findSimilarNodes(node.type, 3);
                     let message = `Unknown node type: "${node.type}".`;
@@ -310,6 +334,9 @@ class WorkflowValidator {
                 if (normalizedType.startsWith('nodes-langchain.')) {
                     continue;
                 }
+                if (nodeInfo.isInferred) {
+                    continue;
+                }
                 const paramsWithVersion = {
                     '@version': node.typeVersion || 1,
                     ...node.parameters