feat(后端架构): 移除实验性GoGPU后端，保留多后端扩展能力

go.mod

@@ -6,7 +6,6 @@ require (
 	github.com/emmansun/gmsm v0.44.1
 	github.com/go-fonts/latin-modern v0.3.3
 	github.com/go-text/typesetting v0.3.5
-	github.com/gogpu/gg v0.52.5
 	github.com/tdewolff/canvas v0.0.0-20260913163248-dd4999d1c76a
 	github.com/tdewolff/font v0.0.0-20260913163313-54f98bb59ee6
 	github.com/xiaoqidun/jbig2 v1.1.1
@@ -25,8 +24,6 @@ require (
 	github.com/andybalholm/brotli v1.2.2 // indirect
 	github.com/benoitkugler/textlayout v0.3.2 // indirect
 	github.com/benoitkugler/textprocessing v0.0.6 // indirect
-	github.com/gogpu/gpucontext v0.28.0 // indirect
-	github.com/gogpu/gputypes v0.5.2 // indirect
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
 	github.com/srwiley/rasterx v0.0.0-20220730225603-2ab79fcdd4ef // indirect
 	github.com/srwiley/scanx v0.0.0-20190309010443-e94503791388 // indirect