fix: resolve multiple n8n_update_partial_workflow bugs (#635)

* fix: use correct MCP SDK API for server capabilities in test

getServerVersion() returns Implementation (name/version only), not the
full init result. Use client.getServerCapabilities() instead to access
server capabilities, fixing the CI typecheck failure.

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

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: resolve multiple n8n_update_partial_workflow bugs (#592, #599, #610, #623, #624, #625, #629, #630, #633)

Phase 1 - Data loss prevention:
- Add missing unary operators (empty, notEmpty, exists, notExists) to sanitizer (#592)
- Preserve positional empty arrays in connections during removeNode/cleanStale (#610)
- Scope sanitization to modified nodes only, preventing unrelated node corruption
- Add empty body {} to activate/deactivate POST calls to fix 415 errors (#633)

Phase 2 - Error handling & response clarity:
- Serialize Zod errors to readable "path: message" strings (#630)
- Add saved:true/false field to all response paths (#625)
- Improve updateNode error hint with correct structure example (#623)
- Track removed node names for better removeConnection errors (#624)

Phase 3 - Connection & type fixes:
- Coerce sourceOutput/targetInput to String() consistently (#629)
- Accept numeric sourceOutput/targetInput at Zod schema level via transform

Phase 4 - Tag operations via dedicated API (#599):
- Track tags as tagsToAdd/tagsToRemove instead of mutating workflow.tags
- Orchestrate tag creation and association via listTags/createTag/updateWorkflowTags
- Reconcile conflicting add/remove for same tag (last operation wins)
- Tag failures produce warnings, not hard errors

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

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add v2.37.0 changelog entry

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

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: resolve pre-existing integration test failures in CI

- Create new MCP Server instance per connection in test helpers (SDK 1.27+
  requires separate Protocol instance per connection)
- Normalize database paths with path.resolve() in shared-database singleton
  to prevent path mismatch errors across test files
- Add no-op catch handler to deferred initialization promise in server.ts
  to prevent unhandled rejection warnings
- Properly call mcpServer.shutdown() in test helper close() to release
  shared database references

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

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/mcp/server.ts

@@ -210,6 +210,13 @@ export class N8NDocumentationMCPServer {
       }
     });
 
+    // Attach a no-op catch handler to prevent Node.js from flagging this as an
+    // unhandled rejection in the interval between construction and the first
+    // await of this.initialized (via ensureInitialized). This does NOT suppress
+    // the error: the original this.initialized promise still rejects, and
+    // ensureInitialized() will re-throw it when awaited.
+    this.initialized.catch(() => {});
+
     logger.info('Initializing n8n Documentation MCP server');
     
     this.server = new Server(