[FEATURE] tab-completion mode similar to bash

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

Add a tab-completion mode for @-file references that lists all matches at once (like bash's default complete behavior), as an alternative to the current cycle-through-matches behavior.

Proposed Solution

Configurable via settings.json or a separate keybinding.

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_