Closes #592
With refaspect, the inset colorbar geometry is finalized during draw. Previously, we were reflowing the inset frame too late (effectively after draw scheduling), so some render paths used stale bounds and the frame no longer wrapped the label correctly.

The fix moves frame reflow into the actual draw path and runs it before artists are painted, using the active renderer. We also mark inset colorbars as needing reflow when created, so the frame is recomputed at the right time. That makes the frame/label layout deterministic across backends and preserves correct wrapping with refaspect.

A regression test was added to lock this behavior.