docs: refactor documentation and upgrade to Node.js 24

This commit upgrades the project to Node.js 24 (LTS) and performs a major refactoring of the documentation to support both advanced users and AI-based automation (MCP).

Changes:
- Environment & CI/CD:
  - Set Node.js version to >=24 in package.json and .nvmrc.
  - Updated Dockerfile to use Node 24 base image.
  - Updated @types/node to ^24.10.9.
- Documentation:
  - Refactored README.md with comprehensive technical reference, configuration details, and Zabbix-to-GraphQL mapping.
  - Created docs/howtos/cookbook.md with practical recipes for common tasks and AI test generation.
  - Updated docs/howtos/mcp.md to emphasize GraphQL's advantages for AI agents and Model Context Protocol.
  - Added readme.improvement.plan.md to track documentation evolution.
  - Enhanced all how-to guides with improved cross-references and up-to-date information.
- Guidelines:
  - Updated .junie/guidelines.md with Node 24 requirements and enhanced commit message standards (Conventional Commits 1.0.0).
- Infrastructure & Code:
  - Updated docker-compose.yml with Apollo MCP server integration.
  - Refined configuration and schema handling in src/api/ and src/datasources/.
  - Synchronized generated TypeScript types with schema updates.

package.json

@@ -9,7 +9,7 @@
     "start": "nodemon --watch \"src/**\" --watch \"schema.graphql\" --ext \"ts,json\" --exec \"node --import tsx ./src/index.ts\"",
     "prod": "npm run copy-schema && node ./dist/index.js",
     "test": "jest --detectOpenHandles --forceExit --bail",
-    "codegen": "graphql-codegen --config codegen.ts --watch \"schema.graphql\"",
+    "codegen": "graphql-codegen --config codegen.ts --watch",
     "nodemon": "nodemon --watch \"src/**\" --watch \"schema.graphql\" --ext \"ts,json\" --exec \"tsc",
     "copy-schema": "cp -R schema ./dist/"
   },
@@ -17,6 +17,9 @@
   "license": "AGPL-3.0-only",
   "author": "Andreas Hilbig",
   "copyright": "All rights reserved by Hilbig IT GmbH",
+  "engines": {
+    "node": ">=24"
+  },
   "dependencies": {
     "@apollo/datasource-rest": "^6.3.0",
     "@apollo/server": "^5.2.0",
@@ -41,7 +44,7 @@
     "@types/cors": "^2.8.17",
     "@types/express": "^5.0.6",
     "@types/jest": "^29.5.13",
-    "@types/node": "^22.6.1",
+    "@types/node": "^24.10.9",
     "@types/simple-mock": "^0.8.6",
     "@types/ws": "^8.5.12",
     "jest": "^29.7.0",