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

eclipse/svg/solar_map_events_title_test.go

@@ -0,0 +1,69 @@
+package svg
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+// EventsTitle 覆盖“全球阶段”数据块的标题；空值使用该块的本地化默认标题。
+func TestSolarEclipseEventsTitleLocalizesAndOverrides(t *testing.T) {
+	for _, test := range []struct {
+		name     string
+		language string
+		title    string
+		want     string
+	}{
+		{name: "zh default", want: "食甚点的地方情况"},
+		{name: "zh override", title: "全球阶段（自定义）", want: "全球阶段（自定义）"},
+		{name: "en default", language: "en", want: "Local circumstances at greatest"},
+		{name: "en override", language: "en", title: "Global phases (custom)", want: "Global phases (custom)"},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			_, circumstances, _ := solarEclipseContactTitles(SolarEclipseMapSVGOptions{
+				Language: test.language, EventsTitle: test.title,
+			})
+			if circumstances != test.want {
+				t.Fatalf("global-phase block title = %q, want %q", circumstances, test.want)
+			}
+		})
+	}
+
+	// 两种版式都要把标题写进产物，横版与竖版各验证一次。
+	for _, layout := range []struct {
+		name          string
+		width, height int
+		language      string
+	}{
+		{name: "landscape", width: 960, height: 640},
+		{name: "portrait", width: 800, height: 820, language: "en"},
+	} {
+		t.Run("rendered/"+layout.name, func(t *testing.T) {
+			title := "全球阶段（自定义）"
+			unwanted := "食甚点的地方情况"
+			if layout.language == "en" {
+				title = "Global phases (custom)"
+				unwanted = "Local circumstances at greatest"
+			}
+			rendered, ok := SolarEclipseMapSVG(
+				time.Date(2024, time.April, 8, 0, 0, 0, 0, time.UTC),
+				SolarEclipseMapSVGOptions{
+					Width: layout.width, Height: layout.height, Location: time.UTC,
+					PartialStep: 10 * time.Minute, Language: layout.language, EventsTitle: title,
+				},
+			)
+			if !ok {
+				t.Fatal("missing 2024-04-08 map")
+			}
+			if !strings.Contains(rendered, title) {
+				t.Fatalf("map is missing the events title %q", title)
+			}
+			if strings.Contains(rendered, unwanted) {
+				t.Fatalf("map still carries the replaced events title %q", unwanted)
+			}
+			if err := validateEclipseMapXML(rendered); err != nil {
+				t.Fatalf("map is not valid XML: %v", err)
+			}
+		})
+	}
+}