Implement Tab Completion & Keyboard Shortcuts

[Apurba-01]

Currently, PromptShell lacks interactive shell features that would significantly enhance user productivity. This feature would implement:

1) Tab completion for internal commands (e.g., !help, !exit)

2) Keyboard shortcuts (Ctrl+L to clear screen, ↑/↓ for history navigation)

3) Persistent command history across sessions

This will transform PromptShell into a more intuitive and efficient CLI tool, aligning it with standard shell experiences like Bash/Zsh.

I am Excited to work on these and contribute to the project...

[Kirti-Rathi]

Assigned!

Regarding the raised issues:

1. !help or help doesn't work as expected and goes to debugging mode, and !exit doesn't work the same as exit

2. While Ctrl+L clears screen, it pushes the CWD to bottom as opposed to the standard terminal behavior, and while ↑/↓ for history navigation works, it's not persistent across sessions.

3. Before you proceed, I’d love to hear your proposed approach for implementing persistent history.

Please ensure that no breaking changes are introduced and backward compatibility is maintained.

Looking forward to your contributions!