Add GitHub Actions workflow for building frontend and installation instructions for RPi

[szh]

Description

This PR adds a GitHub Actions workflow to automate building the React frontend and provides installation instructions for existing Raspberry Pi devices. These changes improve the deployment process and make it easier for users to set up the project.

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

I tested with a Raspberry Pi Zero 2 W and the latest Raspberry Pi Imager.
See discussions in #3

Tested on the following devices:

• Development environment (Linux, Windows, or MacOS)
• Pi Zero 2 W
• Pi Zero W
• Pi 3A+
• Pi 3B+
• Pi 4
• Pi 5

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes