Simplify MCP server to stdio-only (local desktop use)

Drop the Streamable HTTP transport and direct express dependency so the server has no network listener and cannot be reached from web chat — matches the desktop-only use case. Update README/.env.example accordingly. (express remains only as a transitive dep of the MCP SDK; unused.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mcp-server/package.json

@@ -8,12 +8,10 @@
     "sharepoint-lists-mcp": "index.mjs"
   },
   "scripts": {
-    "start": "node index.mjs",
-    "start:http": "node index.mjs --http"
+    "start": "node index.mjs"
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.12.0",
-    "express": "^4.21.0",
     "zod": "^3.23.8"
   }
 }