feat(validator): detect conditional branch fan-out & connection auto-fixes (#622)

* feat(auto-fixer): add 5 connection structure fix types

Add automatic repair for malformed workflow connections commonly
generated by AI models:
- connection-numeric-keys: "0","1" keys → main[0], main[1]
- connection-invalid-type: type:"0" → type:"main" (or parent key)
- connection-id-to-name: node ID refs → node name refs
- connection-duplicate-removal: dedup identical connection entries
- connection-input-index: out-of-bounds input index → clamped

Includes collision-safe ID-to-name renames, medium confidence on
merge conflicts and index clamping, shared CONNECTION_FIX_TYPES
constant, and 24 unit tests.

Concieved by Romuald Członkowski - www.aiadvisors.pl/en


* feat(validator): detect IF/Switch/Filter conditional branch fan-out misuse

Add CONDITIONAL_BRANCH_FANOUT warning when conditional nodes have all
connections on main[0] with higher outputs empty, indicating both
branches execute together instead of being split by condition.

Extract getShortNodeType() and getConditionalOutputInfo() helpers to
deduplicate conditional node detection logic.

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

dist/mcp/handlers-n8n-manager.js

@@ -212,7 +212,13 @@ const autofixWorkflowSchema = zod_1.z.object({
         'node-type-correction',
         'webhook-missing-path',
         'typeversion-upgrade',
-        'version-migration'
+        'version-migration',
+        'tool-variant-correction',
+        'connection-numeric-keys',
+        'connection-invalid-type',
+        'connection-id-to-name',
+        'connection-duplicate-removal',
+        'connection-input-index'
     ])).optional(),
     confidenceThreshold: zod_1.z.enum(['high', 'medium', 'low']).optional().default('medium'),
     maxFixes: zod_1.z.number().optional().default(50)