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

basic/jupiter_satellite_events_test.go

@@ -143,3 +143,39 @@ func mustParseRFC3339Nano(t *testing.T, value string) time.Time {
 	}
 	return date
 }
+
+func TestJupiterGalileanSearchFindsShortGrazingTransit(t *testing.T) {
+	// 2463144 附近 Callisto 有一次擦边凌日：Start 2463143.9993 / Greatest 2463144.0015 /
+	// End 2463144.0038，全场只有 6.4 分钟，整段落在 2 小时粗采样之间。旧实现看不到度量
+	// 凹陷，会把 16.85 天后的下一次凌日当成 "next"（Valid 仍为 true，属静默跳事件）。
+	// Callisto has a grazing transit near 2463144: Start 2463143.9993, Greatest
+	// 2463144.0015, End 2463144.0038 — only 6.4 minutes, entirely between two two-hour
+	// coarse samples. The old search saw no metric dip and reported the next transit 16.85
+	// days later as "next", still with Valid=true (a silent skip).
+	closest := ClosestJupiterGalileanPhenomenonEvent(2463144.0, 4, JupiterGalileanTransit)
+	if !closest.Valid {
+		t.Fatal("no Callisto transit found at 2463144")
+	}
+	if duration := closest.End - closest.Start; duration > 0.01 {
+		t.Fatalf("fixture changed: transit duration %.4f d, want the 6.4-minute grazing event", duration)
+	}
+
+	next := NextJupiterGalileanPhenomenonEvent(2463143.9646, 4, JupiterGalileanTransit)
+	if !next.Valid {
+		t.Fatal("NextJupiterGalileanPhenomenonEvent returned nothing")
+	}
+	if offset := next.Greatest - 2463143.9646; offset > 0.1 {
+		t.Fatalf("next transit is %.3f d away, want the 53-minute one (the search skipped it)", offset)
+	}
+	if math.Abs(next.Greatest-closest.Greatest) > 1e-5 {
+		t.Fatalf("next greatest %.9f, want the same event as closest %.9f", next.Greatest, closest.Greatest)
+	}
+
+	last := LastJupiterGalileanPhenomenonEvent(2463144.05, 4, JupiterGalileanTransit)
+	if !last.Valid {
+		t.Fatal("LastJupiterGalileanPhenomenonEvent returned nothing")
+	}
+	if math.Abs(last.Greatest-closest.Greatest) > 1e-5 {
+		t.Fatalf("last greatest %.9f, want the same event as closest %.9f", last.Greatest, closest.Greatest)
+	}
+}