fix: resolve node type normalization bug blocking all AI validation (HIGH-01, HIGH-04, HIGH-08)

CRITICAL BUG FIX:
NodeTypeNormalizer.normalizeToFullForm() converts TO SHORT form (nodes-langchain.*),
but all validation code compared against FULL form (@n8n/n8n-nodes-langchain.*).
This caused ALL AI validation to be silently skipped.

Impact:
- Missing language model detection: NEVER triggered
- AI tool connection detection: NEVER triggered
- Streaming mode validation: NEVER triggered
- AI tool sub-node validation: NEVER triggered

ROOT CAUSE:
Line 348 in ai-node-validator.ts (and 19 other locations):
  if (normalizedType === '@n8n/n8n-nodes-langchain.agent') // FULL form
But normalizedType is 'nodes-langchain.agent' (SHORT form)
Result: Comparison always FALSE, validation never runs

FIXES:
1. ai-node-validator.ts (7 locations):
   - Lines 551, 557, 563: validateAISpecificNodes comparisons
   - Line 348: checkIfStreamingTarget comparison
   - Lines 417, 444: validateChatTrigger comparisons
   - Lines 589-591: hasAINodes array
   - Lines 606-608, 612: getAINodeCategory comparisons

2. ai-tool-validators.ts (14 locations):
   - Lines 980-991: AI_TOOL_VALIDATORS keys (13 validators)
   - Lines 1015-1037: validateAIToolSubNode switch cases (13 cases)

3. ENHANCED streaming validation:
   - Added validation for AI Agent's own streamResponse setting
   - Previously only checked streaming FROM Chat Trigger
   - Now validates BOTH scenarios (lines 259-276)

VERIFICATION:
- All 25 AI validator unit tests: ✅ PASS
- Debug test (missing LM): ✅ PASS
- Debug test (AI tools): ✅ PASS
- Debug test (streaming): ✅ PASS

Resolves:
- HIGH-01: Missing language model detection (was never running)
- HIGH-04: AI tool connection detection (was never running)
- HIGH-08: Streaming mode validation (was never running + incomplete)

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

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

src/services/ai-tool-validators.ts

@@ -977,18 +977,18 @@ export function validateWolframAlphaTool(node: WorkflowNode): ValidationIssue[]
  * Helper: Map node types to validator functions
  */
 export const AI_TOOL_VALIDATORS = {
-  '@n8n/n8n-nodes-langchain.toolHttpRequest': validateHTTPRequestTool,
-  '@n8n/n8n-nodes-langchain.toolCode': validateCodeTool,
-  '@n8n/n8n-nodes-langchain.toolVectorStore': validateVectorStoreTool,
-  '@n8n/n8n-nodes-langchain.toolWorkflow': validateWorkflowTool,
-  '@n8n/n8n-nodes-langchain.agentTool': validateAIAgentTool,
-  '@n8n/n8n-nodes-langchain.mcpClientTool': validateMCPClientTool,
-  '@n8n/n8n-nodes-langchain.toolCalculator': validateCalculatorTool,
-  '@n8n/n8n-nodes-langchain.toolThink': validateThinkTool,
-  '@n8n/n8n-nodes-langchain.toolSerpApi': validateSerpApiTool,
-  '@n8n/n8n-nodes-langchain.toolWikipedia': validateWikipediaTool,
-  '@n8n/n8n-nodes-langchain.toolSearXng': validateSearXngTool,
-  '@n8n/n8n-nodes-langchain.toolWolframAlpha': validateWolframAlphaTool,
+  'nodes-langchain.toolHttpRequest': validateHTTPRequestTool,
+  'nodes-langchain.toolCode': validateCodeTool,
+  'nodes-langchain.toolVectorStore': validateVectorStoreTool,
+  'nodes-langchain.toolWorkflow': validateWorkflowTool,
+  'nodes-langchain.agentTool': validateAIAgentTool,
+  'nodes-langchain.mcpClientTool': validateMCPClientTool,
+  'nodes-langchain.toolCalculator': validateCalculatorTool,
+  'nodes-langchain.toolThink': validateThinkTool,
+  'nodes-langchain.toolSerpApi': validateSerpApiTool,
+  'nodes-langchain.toolWikipedia': validateWikipediaTool,
+  'nodes-langchain.toolSearXng': validateSearXngTool,
+  'nodes-langchain.toolWolframAlpha': validateWolframAlphaTool,
 } as const;
 
 /**
@@ -1012,29 +1012,29 @@ export function validateAIToolSubNode(
 
   // Route to appropriate validator based on node type
   switch (normalized) {
-    case '@n8n/n8n-nodes-langchain.toolHttpRequest':
+    case 'nodes-langchain.toolHttpRequest':
       return validateHTTPRequestTool(node);
-    case '@n8n/n8n-nodes-langchain.toolCode':
+    case 'nodes-langchain.toolCode':
       return validateCodeTool(node);
-    case '@n8n/n8n-nodes-langchain.toolVectorStore':
+    case 'nodes-langchain.toolVectorStore':
       return validateVectorStoreTool(node, reverseConnections, workflow);
-    case '@n8n/n8n-nodes-langchain.toolWorkflow':
+    case 'nodes-langchain.toolWorkflow':
       return validateWorkflowTool(node);
-    case '@n8n/n8n-nodes-langchain.agentTool':
+    case 'nodes-langchain.agentTool':
       return validateAIAgentTool(node, reverseConnections);
-    case '@n8n/n8n-nodes-langchain.mcpClientTool':
+    case 'nodes-langchain.mcpClientTool':
       return validateMCPClientTool(node);
-    case '@n8n/n8n-nodes-langchain.toolCalculator':
+    case 'nodes-langchain.toolCalculator':
       return validateCalculatorTool(node);
-    case '@n8n/n8n-nodes-langchain.toolThink':
+    case 'nodes-langchain.toolThink':
       return validateThinkTool(node);
-    case '@n8n/n8n-nodes-langchain.toolSerpApi':
+    case 'nodes-langchain.toolSerpApi':
       return validateSerpApiTool(node);
-    case '@n8n/n8n-nodes-langchain.toolWikipedia':
+    case 'nodes-langchain.toolWikipedia':
       return validateWikipediaTool(node);
-    case '@n8n/n8n-nodes-langchain.toolSearXng':
+    case 'nodes-langchain.toolSearXng':
       return validateSearXngTool(node);
-    case '@n8n/n8n-nodes-langchain.toolWolframAlpha':
+    case 'nodes-langchain.toolWolframAlpha':
       return validateWolframAlphaTool(node);
     default:
       return [];