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>

src/mcp/tools-n8n-manager.ts

@@ -484,5 +484,18 @@ Validation example:
       type: 'object',
       properties: {}
     }
+  },
+  {
+    name: 'n8n_diagnostic',
+    description: `Diagnose n8n API configuration and management tools availability. Shows current configuration status, which tools are enabled/disabled, and helps troubleshoot why management tools might not be appearing. Returns detailed diagnostic information including environment variables, API connectivity, and tool registration status.`,
+    inputSchema: {
+      type: 'object',
+      properties: {
+        verbose: {
+          type: 'boolean',
+          description: 'Include detailed debug information (default: false)'
+        }
+      }
+    }
   }
 ];