Add CLAUDE.md project documentation

CLAUDE.md

@@ -0,0 +1,40 @@
+# CLAUDE.md
+
+## Project Overview
+
+Hello-node is a minimal Node.js Express web application serving as a "Hello Azure" demo. It runs an HTTP server with two endpoints.
+
+## Tech Stack
+
+- **Runtime:** Node.js (v22+)
+- **Framework:** Express v5.1.0
+- **Language:** JavaScript (no TypeScript)
+
+## Getting Started
+
+```bash
+npm install       # Install dependencies
+npm start         # Runs: node index.js — starts server on port 3000
+```
+
+The port is configurable via the `PORT` environment variable.
+
+## Project Structure
+
+```
+index.js          # Main application entry point (Express server)
+package.json      # Project config and dependencies
+```
+
+## Endpoints
+
+- `GET /` — Returns greeting text: "Hello from Node.js on Azure!"
+- `GET /hello` — Returns JSON: `{ "message": "Hello, Azure!" }`
+
+## Development Notes
+
+- No build step required — runs native JavaScript directly
+- No test framework is configured
+- No linting or formatting tools are set up
+- No CI/CD pipelines exist
+- Single dependency: `express`