feat: 新增月掩与日月食地理绘图并提升观测计算精度

- 新增月掩恒星和行星：支持搜索、掩甚点、全球掩带及固定地点轨迹计算
- 支持恒星星表坐标转换、有限盘面行星接触事件和月掩 SVG 输出
- 新增日月食及月掩全球投影图、时间标记和 GeoJSON 地理数据接口
- 扩展日食中心线、南北界及偏食足迹采样，支持极区投影
- 修正站心时角、月出月落、月球视半径、折射和恒星自行计算
- 优化内外行星事件搜索、边界选择、极端输入处理和计算稳定性

moon/occultation_star.go

@@ -0,0 +1,25 @@
+package moon
+
+import (
+	"time"
+
+	"b612.me/astro/basic"
+)
+
+// FindStarOccultations 搜索单颗点源恒星的月掩星。
+//
+// 输入坐标从历元传播并转换到当日视坐标系。此函数不会加载内嵌星表；需要星表搜索时，调用者必须显式加载并选择恒星。经度东为正、纬度北为正，单位为度；高度为平均海平面以上米数。
+// FindStarOccultations searches for lunar occultations of one point-source star.
+// The input coordinate is propagated from its epoch and converted to the apparent frame of date. This function never loads the embedded star catalog; callers that need catalog searches must load and select stars explicitly. Longitude is east-positive in degrees, latitude is north-positive in degrees, and height is the observer elevation above mean sea level in meters.
+func FindStarOccultations(start, end time.Time, star StarCoordinate, longitude, latitude, height float64,
+	options OccultationSearchOptions) ([]StarOccultationInfo, error) {
+	return basic.FindStarOccultations(start, end, star, longitude, latitude, height, options)
+}
+
+// FindBestStarOccultations 返回窗口内每次恒星月掩的全球海平面几何掩甚点。
+// 点选择不使用地平线或可见性评分；查询端点使用核心求解器的 10 ms 数值选择容差。
+// FindBestStarOccultations returns the global geometric greatest sea-level point for every stellar occultation whose greatest instant is in the window.
+// The point is selected without a horizon or visibility score. Query endpoints use the core solver's 10 ms numerical selection tolerance.
+func FindBestStarOccultations(start, end time.Time, star StarCoordinate, options OccultationSearchOptions) ([]StarOccultationInfo, error) {
+	return basic.FindBestStarOccultations(start, end, star, options)
+}