feat(后端架构): 接入GoGPU渲染，支持后端切换

ofdgo_geom_path.go

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+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+// GeometryPath 保存独立于绘图库的几何路径，不扁平化曲线或舍入坐标
+// 坐标以左上角为原点，单位为毫米，子路径从Move开始，Close回到当前子路径起点
+type GeometryPath []GeometrySegment
+
+// GeometryVerb 表示几何路径指令
+type GeometryVerb uint8
+
+const (
+	GeometryMove GeometryVerb = iota
+	GeometryLine
+	GeometryQuad
+	GeometryCubic
+	GeometryArc
+	GeometryClose
+)
+
+// GeometrySegment 保存路径端点、贝塞尔控制点或端点式椭圆弧参数
+// 弧线Rotation单位为度，Sweep为true表示顺时针，Large表示大弧
+type GeometrySegment struct {
+	Verb               GeometryVerb
+	End                Point
+	Control1, Control2 Point
+	RadiusX, RadiusY   float64
+	Rotation           float64
+	Large, Sweep       bool
+}