Add CLI --about flag

[kaushikneha551982-boop]

Summary

Adds a new CLI flag --about to display basic project information for Fyzenor in the terminal.

• What does this PR change?

• This PR introduces a new CLI option --about which prints a short description of the Fyzenor project.

• Why is this change needed?

• It improves user experience by allowing users to understand what Fyzenor is without any other documentation.

Type of Change

• Bug fix
• New feature - yes
• Refactor
• Performance improvement
• Documentation update
• CI/CD change
• Other

Changes Made

• Added --about CLI flag in manager.cpp

• Integrated it into existing argument

• Displays project information when used

• List the important code or behavior changes here.

• Mention any UI, preview, install, or keybinding changes explicitly.

Testing

• Built locally - yes
• Ran ./fyzenor --version -yes
• Ran ./fyzenor --help -yes
• Tested interactive behavior manually -yes

Environment

• OS: windows
• Terminal emulator: CMD
• Shell: Powershell

Screenshots or Terminal Output

Add screenshots, recordings, or terminal output if the change affects UI, previews, installation flow, or behavior.
./fyzenor --about
Fyzenor: A modern terminal file manager built in C++
Developed as part of GSSoC contribution.

Checklist

• My code follows the existing style of the project - yes
• I kept the change focused and avoided unrelated edits -yes
• I updated documentation when needed -yes
• I checked that this PR does not break existing behavior knowingly -yes

Notes for Reviewers

This is a small CLI enhancement. No changes were made to existing commands or FileManager logic.

Add anything reviewers should pay special attention to.