Add HTTP/SSE transport with graceful degradation for public deployment

New Features:
- HTTP/SSE server (server-http.js) for network access
- Express-based web server with MCP SSE transport
- Rate limiting (50 req/min per IP)
- Request timeouts (30s)
- Concurrent request limiting (max 10)
- Circuit breaker pattern for failure handling
- Memory monitoring (450MB threshold)
- Gzip compression for responses
- CORS support for cross-origin requests
- Health check endpoint (/health)

Infrastructure:
- Updated package.json with new dependencies (express, cors, compression, rate-limit)
- New npm script: start:http for HTTP server
- Comprehensive deployment guide (DEPLOYMENT.md)
- Updated README with deployment instructions

Graceful Degradation:
- Automatically rejects requests when at capacity
- Circuit breaker opens after 5 failures
- Memory-aware request handling
- Per-IP rate limiting to prevent abuse

The original stdio server (index.js) remains unchanged for local use.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

package.json

@@ -9,12 +9,17 @@
   },
   "scripts": {
     "start": "node index.js",
+    "start:http": "node server-http.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "keywords": ["mcp", "hacker-public-radio", "hpr", "podcast", "knowledge-base"],
   "author": "",
   "license": "CC-BY-SA",
   "dependencies": {
-    "@modelcontextprotocol/sdk": "^1.20.2"
+    "@modelcontextprotocol/sdk": "^1.20.2",
+    "express": "^4.18.2",
+    "cors": "^2.8.5",
+    "compression": "^1.7.4",
+    "express-rate-limit": "^7.1.5"
   }
 }