Module renderer 

WgpuBackend: headless GPU RenderBackend implementing Tier 1 primitives and gradient fills.

Supported DrawCommand variants

Command	Pipeline	Notes
PushClip / PopClip	solid	Hardware scissor via ClipStack
FillRect	solid	kind=0 solid quad
FillCircle	solid	kind=1 SDF disc
StrokeRect	solid	4 thin edge quads
FillRoundedRect	solid	kind=2 SDF rounded rect
FillRoundedRectPerCorner	solid	kind=3 SDF per-corner rounded rect
FillEllipse	solid	kind=4 SDF ellipse
Line	solid	kind=5 hard-clip line
LineAa	solid	kind=5 AA line
LineThick	solid	kind=5 AA line with custom width
LineDashed	solid	CPU-split into solid segments
FillPath	solid	CPU fan-tessellation
StrokePath	solid	CPU stroke-expansion
LinearGradient	gradient	per-draw uniform + gradient quad
RadialGradient	gradient	per-draw uniform + gradient quad

Out-of-scope (deferred)

Image, NineSlice, BoxShadow, DrawText — require texture atlas / blur pipeline and are left in the wildcard arm with an honest comment.

Structs

WgpuBackend

Headless GPU backend implementing RenderBackend.