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.

docs/howtos/cookbook.md

@@ -0,0 +1,87 @@
+# Zabbix GraphQL API Cookbook
+
+This cookbook provides step-by-step "recipes" for common tasks. These instructions are designed to be easy for humans to follow and structured enough for AI agents (using the MCP server) to generate test cases.
+
+## 🤖 AI-Based Test Generation
+
+To generate a test case from a recipe:
+1. Start the `zabbix-graphql` MCP server.
+2. Provide the recipe to your AI agent.
+3. Ask the agent to "Implement a test case for this recipe using the Zabbix GraphQL API".
+4. The agent will use the MCP server to explore the schema and generate appropriate GraphQL operations.
+
+---
+
+## 🍳 Recipe: Extending Schema with a New Device Type
+
+This recipe shows how to add support for a new specialized device type without modifying the core API code.
+
+### Prerequisites
+- Zabbix Template Group `Templates/Roadwork/Devices` exists.
+- Zabbix GraphQL API is running.
+
+### Step 1: Define the Schema Extension
+Create a new `.graphql` file in `schema/extensions/` (e.g. `distance_tracker.graphql`):
+```graphql
+type DistanceTrackerDevice {
+  id: String
+  name: String
+  location: Location
+  distance: Float
+  batteryLevel: Float
+  lastSeen: DateTime
+}
+```
+
+### Step 2: Configure Environment Variables
+Add the new schema and resolver to your `.env` file:
+```env
+ADDITIONAL_SCHEMAS=./schema/extensions/distance_tracker.graphql
+ADDITIONAL_RESOLVERS=DistanceTrackerDevice
+```
+Restart the API server.
+
+### Step 3: Import the Template
+Execute the `importTemplates` mutation to create the template in Zabbix. Use Zabbix item keys that match your GraphQL fields (e.g. `distance.current` for `distance`).
+
+---
+
+## 🍳 Recipe: Provisioning a New Host
+
+### Prerequisites
+- A target Host Group exists in Zabbix.
+- At least one Template exists in Zabbix.
+
+### Step 1: Prepare the Host Object
+Define the host name, groups, and templates to link.
+
+### Step 2: Execute `createHost` Mutation
+```graphql
+mutation CreateNewHost($host: String!, $groups: [Int!]!, $templates: [Int!]!) {
+  createHost(host: $host, hostgroupids: $groups, templateids: $templates) {
+    hostids
+    error {
+      message
+    }
+  }
+}
+```
+
+---
+
+## 🍳 Recipe: Managing User Permissions
+
+### Step 1: Create Permission Template Group
+Create a template group with the prefix `Permissions/` in Zabbix (e.g. `Permissions/Read-Only-Access`).
+
+### Step 2: Assign to User Group
+In Zabbix, give a User Group `Read` access to this template group.
+
+### Step 3: Verify via API
+```graphql
+query CheckMyPermissions {
+  hasPermissions(permissions: [
+    { objectName: "Read-Only-Access", permission: READ }
+  ])
+}
+```