feat: 完善时标与天象几何计算并扩展输出接口

- 新增时标、ΔT 模型、质心时间与 UT1 支持
- 改进日月食、月掩、行星事件及路径边界计算
- 完善恒星三维自行与动态距离传播
- 扩展 SVG、GeoJSON、KML 输出与底层距离换算工具
- 整理中英文手册、示例资源及回归测试

saturn/physical_test.go

@@ -10,11 +10,11 @@ import (
 
 func TestPhysicalWrapperMatchesBasic(t *testing.T) {
 	date := time.Date(2026, 4, 28, 9, 30, 45, 0, time.UTC)
-	jde := basic.Date2JDE(date.UTC())
+	jde := basic.Date2JD(date.UTC())
 
 	got := Physical(date)
 	gotN := PhysicalN(date, -1)
-	want := basic.SaturnPhysicalN(basic.TD2UT(jde, true), -1)
+	want := basic.SaturnPhysicalN(basic.UTC2TT(jde), -1)
 
 	assertSamePhysicalFloat(t, "SubEarthLongitude", got.SubEarthLongitude, want.SubEarthLongitude)
 	assertSamePhysicalFloat(t, "SubEarthLatitude", got.SubEarthLatitude, want.SubEarthLatitude)