fix: mcpTrigger nodes no longer flagged as disconnected (#503) (#506)

Fixed validation bug where mcpTrigger nodes were incorrectly flagged as
"disconnected nodes" when using n8n_update_partial_workflow or
n8n_update_full_workflow. This blocked ALL updates to MCP server workflows.

Changes:
- Extended validateWorkflowStructure() to check all 7 connection types
  (main, error, ai_tool, ai_languageModel, ai_memory, ai_embedding, ai_vectorStore)
- Updated trigger node validation to accept either outgoing OR inbound connections
- Added 7 new tests covering all AI connection types

Fixes #503

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>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp",
-  "version": "2.31.0",
+  "version": "2.31.1",
   "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",