Feature Request: Make thinking block toggle keybinding configurable (Tab vs Alt+T)

Summary

Request to make the keybinding for toggling thinking block expansion/collapse configurable, or restore Tab as the default toggle key.

Current Behavior

The thinking block toggle appears to use Alt+T as the keybinding.

Requested Behavior

Either:

1. Preferred: Make the keybinding configurable via settings (e.g., settings.json or environment variable)
2. Alternative: Restore Tab as the default toggle key for thinking blocks

Use Case

• Tab is more ergonomic and faster to access than Alt+T
• Tab is a common toggle key in terminal applications
• Users with keyboard layouts where Alt combinations are awkward would benefit from configurability

Environment

• Claude Code version: 2.0.73
• Platform: macOS (Darwin)
• Terminal: Various (iTerm2, Terminal.app, etc.)

Additional Context

This would be a small quality-of-life improvement for users who frequently toggle thinking blocks during conversations.