feat: add MCP server package for npx distribution (#284)

* feat: add MCP server package for npx distribution

- Self-contained MCP server with embedded HTTP server
- Real-time browser preview via draw.io iframe
- Tools: start_session, display_diagram, edit_diagram, get_diagram, export_diagram
- Port retry limit (6002-6020) and session TTL cleanup (1 hour)
- Published as @next-ai-drawio/mcp-server on npm

* chore: bump version to 0.1.2

* docs: add MCP server section to README (preview feature)

* docs: add multi-client installation instructions for MCP server

* fix: exclude packages from Next.js build

* docs: use @latest instead of -y flag for npx (match Playwright MCP style)

* chore: bump version to 0.4.3 and add release notes

* chore: remove release notes

* feat: add MCP server notice to example panel

README.md

@@ -30,6 +30,7 @@ https://github.com/user-attachments/assets/9d60a3e8-4a1c-4b5e-acbb-26af2d3eabd1
   - [Table of Contents](#table-of-contents)
   - [Examples](#examples)
   - [Features](#features)
+  - [MCP Server (Preview)](#mcp-server-preview)
   - [Getting Started](#getting-started)
     - [Try it Online](#try-it-online)
     - [Run with Docker (Recommended)](#run-with-docker-recommended)
@@ -92,6 +93,36 @@ Here are some example prompts and their generated diagrams:
 -   **Cloud Architecture Diagram Support**: Specialized support for generating cloud architecture diagrams (AWS, GCP, Azure)
 -   **Animated Connectors**: Create dynamic and animated connectors between diagram elements for better visualization
 
+## MCP Server (Preview)
+
+> **Preview Feature**: This feature is experimental and may change.
+
+Use Next AI Draw.io with AI agents like Claude Desktop, Cursor, and VS Code via MCP (Model Context Protocol).
+
+```json
+{
+  "mcpServers": {
+    "drawio": {
+      "command": "npx",
+      "args": ["@next-ai-drawio/mcp-server@latest"]
+    }
+  }
+}
+```
+
+### Claude Code CLI
+
+```bash
+claude mcp add drawio -- npx @next-ai-drawio/mcp-server@latest
+```
+
+Then ask Claude to create diagrams:
+> "Create a flowchart showing user authentication with login, MFA, and session management"
+
+The diagram appears in your browser in real-time!
+
+See the [MCP Server README](./packages/mcp-server/README.md) for VS Code, Cursor, and other client configurations.
+
 ## Getting Started
 
 ### Try it Online