refactor: clean up file names and fix version management

- Renamed files to remove unnecessary suffixes:
  - tools-update.ts → tools.ts
  - server-update.ts → server.ts
  - http-server-fixed.ts → http-server.ts
- Created version utility to read from package.json as single source of truth
- Updated all imports across 21+ files
- Removed legacy files:
  - src/http-server.ts (legacy HTTP server with known issues)
  - src/utils/n8n-client.ts (unused legacy API client)
- Added n8n_diagnostic tool to help troubleshoot management tools visibility
- Added script to sync package.runtime.json version
- Fixed version mismatch issue (was hardcoded 2.4.1, now reads 2.7.0 from package.json)

This addresses GitHub issue #5 regarding version mismatch and provides better diagnostics for users.

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

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

scripts/test-essentials.ts

@@ -9,7 +9,7 @@
  * 4. Tests the property search functionality
  */
 
-import { N8NDocumentationMCPServer } from '../src/mcp/server-update';
+import { N8NDocumentationMCPServer } from '../src/mcp/server';
 import { readFileSync, writeFileSync } from 'fs';
 import { join } from 'path';