feat: 完善日月食与月掩几何链路并扩展历法接口

- 新增日月食中心带、偏食带、阴影足迹、等时线、食分线及升落边界计算，支持极区与混合食拓扑
- 新增日食单时刻阴影求解器、站心状态查询、批量采样和 ΔT 覆盖接口
- 重构恒星与行星月掩路径，补充有限盘面接触、站心修正、掩带宽度、极区投影及升落边界
- 扩展 SVG 与 GeoJSON 输出，支持详细面板、全球/极区/地球投影、边界闭合、时间标记和拓扑签名
- 扩展日月食候选搜索、局地搜索、沙罗序列预计算与范围外推，补充系列锚点和成员一致性校验
- 补齐古历纪年、儒略历独有闰日、多公历候选、历法改革跨日及精确日期运算接口
- 优化 ΔT、章动、恒星时、月球地平线、事件根搜索和本地星历缓存，降低重复计算开销并提升边界稳定

geojson/solar_hybrid_sampling_regression_test.go

@@ -0,0 +1,48 @@
+package geojson_test
+
+import (
+	"encoding/json"
+	"math"
+	"testing"
+	"time"
+
+	"b612.me/astro/eclipse"
+	"b612.me/astro/geojson"
+)
+
+func TestSolarHybridThinComponentsDoNotCross(t *testing.T) {
+	for _, date := range [][3]int{{881, 3, 4}, {985, 7, 20}, {1703, 1, 17}, {2386, 4, 29}, {3405, 7, 18}, {3667, 1, 7}} {
+		day := time.Date(date[0], time.Month(date[1]), date[2], 0, 0, 0, 0, time.UTC)
+		t.Run(day.Format("2006-01-02"), func(t *testing.T) {
+			partial, ok := eclipse.SolarEclipsePartialFootprints(day, eclipse.SolarEclipsePartialFootprintOptions{
+				Step: 5 * time.Minute, CentralShadowStep: 5 * time.Minute, RiseSetStep: 2 * time.Minute, BoundaryPoints: 96,
+			})
+			if !ok {
+				t.Fatal("missing solar eclipse")
+			}
+			data, err := geojson.MarshalSolarEclipse(partial, nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			band := featureWithRole(t, decodeCollection(t, data), "central-band")
+			var polygons [][][][]float64
+			if err := json.Unmarshal(band.Geometry.Coordinates, &polygons); err != nil {
+				t.Fatal(err)
+			}
+			for pi, polygon := range polygons {
+				for _, ring := range polygon {
+					for i := 0; i+1 < len(ring); i++ {
+						for j := i + 2; j+1 < len(ring); j++ {
+							if i == 0 && j+1 == len(ring)-1 || math.Abs(ring[i][0]) == 180 && math.Abs(ring[i+1][0]) == 180 || math.Abs(ring[j][0]) == 180 && math.Abs(ring[j+1][0]) == 180 {
+								continue
+							}
+							if geoJSONSegmentsCross(ring[i], ring[i+1], ring[j], ring[j+1]) {
+								t.Fatalf("component %d crosses itself at edges %d/%d", pi, i, j)
+							}
+						}
+					}
+				}
+			}
+		})
+	}
+}