Choosing a perspective tool shows the grid, but the canvas also re-selected the tool after a
Cmd-drag with the borrowed Selection tool, so a grid hidden with the tool chosen came back after
any Cmd-drag. `Session::switch_tool` (and the app's `restore_tool`) switch without choosing; the
temporary-tool return uses it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>