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

basic/occultation_planet_footprint.go

@@ -440,7 +440,7 @@ func planetOccultationFootprintAtWithResolution(
 	if !ok {
 		return PlanetOccultationFootprint{}, false
 	}
-	siderealDegrees := ApparentSiderealTime(TD2UT(tt, false)) * 15
+	siderealDegrees := ApparentSiderealTime(TT2UT1(tt)) * 15
 	samples := make([]planetOccultationFootprintSample, boundaryPoints)
 	for index := range samples {
 		theta := 2 * math.Pi * float64(index) / float64(len(samples))
@@ -954,7 +954,7 @@ func planetOccultationHorizonCircle(
 	secondAxis := occultationPathCross(centerDirection, firstAxis)
 	centerDistance := 1 / distance
 	circleRadius := math.Sqrt(math.Max(0, 1-centerDistance*centerDistance))
-	siderealDegrees := ApparentSiderealTime(TD2UT(tt, false)) * 15
+	siderealDegrees := ApparentSiderealTime(TT2UT1(tt)) * 15
 	points := make([]OccultationPathPoint, count)
 	for index := range points {
 		angle := 2 * math.Pi * float64(index) / float64(count)