feat: Add charmebracelet-gum feature

[sebst]

Closes #65

[Copilot]

Pull Request Overview

This PR adds support for installing the charmbracelet/gum CLI tool as a devcontainer feature. It follows the established pattern in this repository for adding new features.

• Implements a new devcontainer feature for the gum binary from Charmbracelet
• Uses GitHub releases to download and install the appropriate binary for the system architecture
• Includes automated testing to verify the installation

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/charmbracelet-gum/devcontainer-feature.json	Defines the feature metadata with configurable version option
src/charmbracelet-gum/install.sh	Installation script that downloads and installs gum binary from GitHub releases
test/charmbracelet-gum/test.sh	Test script to verify gum is installed and functional
.github/workflows/test.yaml	Adds charmbracelet-gum to the CI test matrix

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[Copilot]

The commented-out code for architecture mapping should be removed or implemented. The current implementation returns uname -m output directly (e.g., 'x86_64', 'aarch64'), which must match the naming convention used in the gum release archives. If the releases use different architecture names, this mapping logic should be uncommented and corrected.

Suggested change

	# if [[ "$arch" == "aarch64" ]]; then
	# arch="arm64"
	# elif [[ "$arch" == "x86_64" ]]; then
	# arch="x64"
	# fi
	if [[ "$arch" == "aarch64" ]]; then
	arch="arm64"
	elif [[ "$arch" == "x86_64" ]]; then
	arch="x64"
	fi

[Copilot]

This commented-out line with '--- IGNORE ---' should be removed as it serves no purpose and clutters the code.

Suggested change

# echo "$(dpkg --print-architecture)" --- IGNORE ---