Add full stack Node.js solution

[IEvangelist]

Add full stack Node.js solution, this PR:

• Demonstrates an end-to-end JavaScript solution, that's orchestrated by .NET Aspire.
• Adds a simple app host project.
• Adds an api express-based Node.js app that serves random weather forecast data (much like the ASP.NET Core Minimal API template).
• Adds an app that's copied from the existing React bits in the JavaScript samples.

Contributes to dotnet/docs-aspire#2767

[Copilot]

Pull Request Overview

This pull request introduces a full stack Node.js solution integrated with a .NET Aspire host to demonstrate an end-to-end JavaScript solution with a Node.js API and a React frontend.

• Adds sample documentation describing the architecture and prerequisites.
• Configures the .NET Aspire host to run both the Node.js API and React app.
• Implements a simple Express API returning random weather forecast data and a corresponding React app that consumes it.

Reviewed Changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
samples/FullStackJS/README.md	Documentation introducing the full stack solution and its usage
samples/FullStackJS/FullStackJS.AppHost/Program.cs	Configuration of the .NET Aspire host and integration of Node apps
samples/FullStackJS/api/index.ts	Express API serving random weather data
samples/FullStackJS/app/webpack.config.js	Webpack configuration for the React app with proxy settings
samples/FullStackJS/app/src/index.js	Entry point for the React app
samples/FullStackJS/app/src/components/App.js	React component fetching and displaying weather forecast data

[davidfowl]

We should look into optimizations we can do with node docker files. They are many.