fix(p0): remove incorrect node type normalization before n8n API calls

## Bug Description
handleCreateWorkflow and handleUpdateFullWorkflow were incorrectly
normalizing node types from FULL form (n8n-nodes-base.webhook) to
SHORT form (nodes-base.webhook) before validation and API calls.

This caused 100% failure rate for workflow creation because:
- n8n API requires FULL form (n8n-nodes-base.*)
- Database stores SHORT form (nodes-base.*)
- NodeTypeNormalizer converts TO SHORT form (for database)
- But was being used BEFORE API calls (incorrect)

## Root Cause
NodeTypeNormalizer was designed for database lookups but was
incorrectly applied to API operations. The method name
`normalizeToFullForm()` is misleading - it actually normalizes
TO SHORT form.

## Changes
1. handlers-n8n-manager.ts:
   - Removed NodeTypeNormalizer.normalizeWorkflowNodeTypes() from
     handleCreateWorkflow (line 288)
   - Removed normalization from handleUpdateFullWorkflow (line 544-557)
   - Added proactive SHORT form detection with helpful errors
   - Added comments explaining n8n API expects FULL form

2. node-type-normalizer.ts:
   - Added prominent WARNING about not using before API calls
   - Added examples showing CORRECT vs INCORRECT usage
   - Clarified this is FOR DATABASE OPERATIONS ONLY

3. handlers-n8n-manager.test.ts:
   - Fixed test to expect FULL form (not SHORT) sent to API
   - Removed incorrect expectedNormalizedInput assertion

4. NEW: workflow-creation-node-type-format.test.ts:
   - 7 integration tests with real validation (unmocked)
   - Tests FULL form acceptance, SHORT form rejection
   - Tests real-world workflows (webhook, schedule trigger)
   - Regression test to prevent bug reintroduction

## Verification
Before fix:
❌ Manual Trigger → Set: FAILED
❌ Webhook → HTTP Request: FAILED
Failure rate: 100%

After fix:
✅ Manual Trigger → Set: SUCCESS (ID: kTAaDZwdpzj8gqzM)
✅ Webhook → HTTP Request: SUCCESS (ID: aPtQUb54uuHIqX52)
✅ All 39 tests passing (32 unit + 7 integration)
Success rate: 100%

## Impact
- Fixes: Complete blocking bug preventing all workflow creation
- Risk: Zero (removing buggy behavior)
- Breaking: None (external API unchanged)

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

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

tests/unit/mcp/handlers-n8n-manager.test.ts

@@ -231,20 +231,9 @@ describe('handlers-n8n-manager', () => {
         message: 'Workflow "Test Workflow" created successfully with ID: test-workflow-id',
       });
 
-      const expectedNormalizedInput = {
-        name: 'Test Workflow',
-        nodes: [{
-          id: 'node1',
-          name: 'Start',
-          type: 'nodes-base.start',
-          typeVersion: 1,
-          position: [100, 100],
-          parameters: {},
-        }],
-        connections: testWorkflow.connections,
-      };
-      expect(mockApiClient.createWorkflow).toHaveBeenCalledWith(expectedNormalizedInput);
-      expect(n8nValidation.validateWorkflowStructure).toHaveBeenCalledWith(expectedNormalizedInput);
+      // Should send input as-is to API (n8n expects FULL form: n8n-nodes-base.*)
+      expect(mockApiClient.createWorkflow).toHaveBeenCalledWith(input);
+      expect(n8nValidation.validateWorkflowStructure).toHaveBeenCalledWith(input);
     });
 
     it('should handle validation errors', async () => {