e23b504201
Avoid mutating ImGui draw lists in place by scaling clip rects locally during scissor computation instead of calling ScaleClipRects. This prevents clip rects from growing exponentially on persistent draw lists, such as streamed remote UI. Additionally, clamp the scaled clip rects to the viewport boundaries to prevent Filament's scissor test from rejecting out-of-bounds rects, while avoiding resetting to full-window scissors which would disable clipping. The draw geometry is now immutable in the Update function (ImGui texture state is still mutated). PiperOrigin-RevId: 954277141 Change-Id: Ifdf6866bb4eabaca44b020ea40acc246428b4f0b