[FEATURE] Full interactive shell experience replacing/improving the Bash mode

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Bash mode (commands with ! prefix) lacks features that the daily interactive shell provides, like command completion, history navigation, and everything I customized the shell for.

Proposed Solution

Provide the full command shell experience as if running commands directly in a terminal. This is the shell equivalent of <kbd>Ctrl+G</kbd>, allowing us to use preferred editors.

Alternative Solutions

There is no alternative solution available during the Claude Code session.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

Anyone who spends a lot of time in terminals would definitely know the boost in productivity. I'd like to see fzf command history search, argument suggestions, tab completions, and so on.

Additional Context

_No response_