fix: resolve 5 bugs in n8n_manage_datatable row operations and error handling

Fix critical issues found during staging QA testing:

1. data parameter serialization: MCP transport sends JSON as strings —
   added z.preprocess coercers (coerceJsonArray, coerceJsonObject,
   coerceJsonFilter) to parse string→JSON before Zod validation

2. filter/sortBy URL encoding: n8n API requires URL-encoded query params —
   added encodeURIComponent() for filter and sortBy in getRows/deleteRows

3. json column type: n8n API only accepts string|number|boolean|date —
   removed json from enum in types, Zod schema, tool definition, and docs

4. 404 error messages: N8nNotFoundError was wrapping API messages in
   "Resource with ID <message> not found" — now passes through cleanly

5. Unit test expectations updated for URL-encoded filter/sortBy values

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

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp",
-  "version": "2.40.0",
+  "version": "2.40.1",
   "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",