Bring back a clickable expand/collapse arrow for thinking blocks (mouse, not keyboard)

Is your feature request related to a problem?

Earlier versions of Claude Code showed a clickable arrow/chevron next to thinking blocks that let me expand and collapse them with the mouse. That affordance is gone — thinking is now collapsed gray text that can only be toggled with a keyboard shortcut (Ctrl+O / verbose mode).

This is a real problem in the VSCode extension specifically: Ctrl+O is captured by VSCode itself (Open File), and Alt+T triggers the VSCode menu bar on Windows, so the default shortcuts never reach the Claude panel. I can work around it by rebinding in ~/.claude/keybindings.json, but that is not discoverable for most users.

Describe the solution you'd like

A clickable expand/collapse arrow (chevron) on each thinking block, so it can be opened and closed with the mouse at will — independent of keyboard shortcuts. Ideally per-block, not just an all-or-nothing verbose toggle.

Describe alternatives you've considered

• Keyboard shortcut (Ctrl+O) — conflicts with VSCode's own bindings in the extension.
• Rebinding via keybindings.json — works, but undiscoverable and still keyboard-only.

Additional context

• Environment: Claude Code VSCode extension on Windows 11.
• Mouse-driven users and accessibility setups benefit from a visible, clickable control rather than memorizing/rebinding shortcuts.