chore: update n8n to 1.123.4 and bump version to 2.28.9 (#478)

- Updated n8n from 1.122.4 to 1.123.4
- Updated n8n-core from 1.121.1 to 1.122.1
- Updated n8n-workflow from 1.119.1 to 1.120.0
- Updated @n8n/n8n-nodes-langchain from 1.121.1 to 1.122.1
- Rebuilt node database with 545 nodes (439 from n8n-nodes-base, 106 from @n8n/n8n-nodes-langchain)
- Updated README badge with new n8n version
- Updated CHANGELOG with dependency changes

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 <noreply@anthropic.com>

dist/mcp/server.js

@@ -150,7 +150,17 @@ class N8NDocumentationMCPServer {
     async close() {
         try {
             await this.server.close();
-            this.cache.clear();
+            this.cache.destroy();
+            if (this.db) {
+                try {
+                    this.db.close();
+                }
+                catch (dbError) {
+                    logger_1.logger.warn('Error closing database', {
+                        error: dbError instanceof Error ? dbError.message : String(dbError)
+                    });
+                }
+            }
             this.db = null;
             this.repository = null;
             this.templateService = null;