Fix shell script security vulnerabilities, reliability issues, and enhance CLI experience

[Copilot]

Comprehensive security and quality improvements across all shell scripts in the dotfiles repository, plus major CLI experience enhancements.

Security Fixes

Command Injection - Unquoted variables in git config allowed arbitrary command execution:

# Before: vulnerable to injection if username contains semicolons
git config --global user.name $USERNAME

# After: properly quoted
git config --global user.name "$USERNAME"

Word Splitting - Unquoted variable expansions throughout ($HOME, $PWD, $ZSH_CUSTOM, etc.) could cause failures with paths containing spaces or special characters. All variable expansions now quoted.

Format String Vulnerabilities - Printf calls in prompt_for_multiselect.sh used variables directly in format strings. Now use proper format specifiers.

Reliability Improvements

Directory Traversal - Font installation cd commands left script in wrong directory on failure. Now isolated in subshells:

(cd "${HOME}/Library/Fonts" && curl -fLo "..." https://...)

Git Clone Idempotency - ZSH plugin installations failed on re-runs. Added existence checks before cloning.

ASDF Plugin Installation - Added || true to plugin-add commands for idempotent execution.

Error Handling - Added error checking for Oh My Zsh installation, Nerd Font downloads, and other critical operations with proper status reporting.

Code Quality

• Replaced deprecated expr substr $(uname) with [[ "$(uname)" == Linux* ]]
• Replaced backticks with $() notation
• Added -r flag to read commands to prevent backslash interpretation
• Changed let to (( )) arithmetic syntax
• Added shebangs to sourced scripts
• Fixed git-prune-branches to handle branch names with spaces using while read instead of for loop with command substitution

CLI Experience Enhancements

Visual Improvements:

• Added color support with automatic TTY detection (colors disabled in non-TTY environments)
• Unicode symbols for visual feedback: ✓ (success), ✗ (error), ⚠ (warning), ℹ (info), ► (steps), ▸ (sections)
• Styled headers with box drawing characters
• Welcome banner with ASCII art
• Progress indicators showing step counts (e.g., "Step 2/5")

New Features:

• --help / -h flag: Display comprehensive usage information
• --yes / -y flag: Non-interactive mode with default selections
• Helper functions for consistent messaging: print_header(), print_step(), print_success(), print_error(), print_warning(), print_info(), print_section()

Installation Summary:

• Categorized status report at completion showing:
  • Successfully installed components (green checkmarks)
  • Skipped components already present (yellow indicators)
  • Failed installations (red X marks)
• "Next steps" guidance after successful installation

Stats: 6 files modified, +390/-160 lines

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Code review</issue_title>
<issue_description>Review all the code and generate a report
Implement improvements</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Code review #1

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[noofreuuuh]

@copilot Improve the cli experience

[Copilot]

@copilot Improve the cli experience

Enhanced the CLI experience with the following improvements (commit ca8a406):

Visual Enhancements:

• Added color support (green for success, red for errors, yellow for warnings, blue for info)
• Created styled headers with box drawing characters and Unicode symbols (✓ ✗ ⚠ ℹ ►)
• Added welcome banner with ASCII art

Functionality:

• Implemented --help flag to display usage information
• Added --yes flag for non-interactive installation with defaults
• Created helper functions for consistent messaging across all installation steps

Progress Tracking:

• Step indicators showing current progress (e.g., "Step 2/5")
• Installation summary at the end categorizing components as:
  • Successfully installed (green checkmarks)
  • Skipped/already installed (yellow indicators)
  • Failed (red X marks with exit code)

User Guidance:

• "Next steps" section after successful installation
• Clear instructions for post-installation configuration

The script now provides a much more professional and user-friendly installation experience.