Use escaped double quotes in npm scripts for Windows compatibility

Single quotes in `concurrently` commands work on Unix shells but not on
Windows Command Shell (`cmd.exe`), causing the `INPUT` environment
variable to not be set and npm scripts to fail with errors like:

    'cross-env' is not recognized as an internal or external command
    Error: INPUT environment variable is not set

Replace single quotes with escaped double quotes (`\"`) in npm scripts
in all example `package.json` files.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

examples/basic-server-react/package.json

@@ -28,7 +28,7 @@
     "watch": "cross-env INPUT=mcp-app.html vite build --watch",
     "serve": "bun --watch main.ts",
     "start": "cross-env NODE_ENV=development npm run build && npm run serve",
-    "dev": "cross-env NODE_ENV=development concurrently 'npm run watch' 'npm run serve'",
+    "dev": "cross-env NODE_ENV=development concurrently \"npm run watch\" \"npm run serve\"",
     "prepublishOnly": "npm run build"
   },
   "dependencies": {