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

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dist/services/workflow-validator.d.ts

@@ -1,5 +1,6 @@
 import { NodeRepository } from '../database/node-repository';
 import { EnhancedConfigValidator } from './enhanced-config-validator';
+export declare const VALID_CONNECTION_TYPES: Set<string>;
 interface WorkflowNode {
     id: string;
     name: string;