feat: optimize development experience in GitHub Codespaces

[glaucia86]

The repository already has a configured devcontainer, but we can further enhance the experience by ensuring that users can start the project even faster and with a more streamlined setup inside GitHub Codespaces.

---

Proposed Improvements:

1️⃣ Automate Project Initialization

• Currently, users must manually run npm start after Codespaces loads.
• We can automate this process so that the project starts as soon as Codespaces is ready.

Suggested update to postCreateCommand:

"postCreateCommand": "npm install -g ollamazure tsx; npm ci; cd videos/demos && npm ci && cd ../.. && npm start"

✅ Impact: The project starts automatically when opening Codespaces, reducing manual steps.

---

2️⃣ Improve Instructions in README

• Update the README steps to clearly indicate that the project automatically installs dependencies and starts running.
• Highlight the Codespaces button for better visibility.

Suggested README update:

## 🚀 Quick Start with GitHub Codespaces  
Click the button below to start coding instantly:  

[![Open in GitHub Codespaces](https://img.shields.io/badge/Open%20in-GitHub%20Codespaces-blue?logo=github)](https://codespaces.new/microsoft/generative-ai-with-javascript)  

Once the Codespaces environment loads, the project will **automatically install dependencies and start running**. No need to run extra commands!  

✅ Impact: Improves onboarding experience and reduces manual steps.

---

3️⃣ Improve Performance by Pre-Installing Dependencies

Installing dependencies inside Codespaces can slow down the first-time setup. Instead of relying on fresh npm install runs, we can pre-install dependencies inside a Dockerfile to speed up initialization.

📌 Suggested changes:

1. Modify .devcontainer/devcontainer.json to use a Dockerfile:

{
  "build": {
    "dockerfile": "Dockerfile"
  }
}

2. Create a Dockerfile in .devcontainer/ with:

FROM mcr.microsoft.com/devcontainers/javascript-node:20-bullseye
WORKDIR /workspace
COPY package.json package-lock.json ./
RUN npm ci
COPY . .

✅ Impact: Dependencies are pre-installed during the container build, reducing the setup time when launching Codespaces.

---