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

moon/svg/occultation_planet_local_test.go

@@ -2,6 +2,7 @@ package svg
 
 import (
 	"errors"
+	"fmt"
 	"math"
 	"strings"
 	"testing"
@@ -52,6 +53,26 @@ func TestFindLocalPlanetOccultationSVGsSaturnFiveContacts(t *testing.T) {
 	}
 }
 
+func TestLocalPlanetOccultationSVGUsesGreatestMoonPhase(t *testing.T) {
+	info := localSaturnOccultation(t)
+	diagram, err := LocalPlanetOccultationSVG(info, LocalPlanetOccultationSVGOptions{
+		Location: time.UTC,
+	})
+	if err != nil {
+		t.Fatalf("LocalPlanetOccultationSVG() error = %v", err)
+	}
+	appearance := localOccultationMoonAppearanceAt(info.Greatest, info.Observer)
+	want := fmt.Sprintf(`data-illumination="%.6f" data-bright-limb-position-angle="%.3f"`,
+		appearance.illumination, appearance.brightLimbPA)
+	if !strings.Contains(diagram, want) {
+		t.Fatalf("local planetary SVG does not carry greatest-time Moon appearance %q", want)
+	}
+	if appearance.illumination > 1e-6 && appearance.illumination < 1-1e-6 &&
+		!strings.Contains(diagram, `<clipPath id="local-planet-occultation-moon-overview">`) {
+		t.Fatal("non-full Moon overview is missing its phase clip path")
+	}
+}
+
 func TestLocalPlanetOccultationSVGStageCentersPreserveDisplayedTangency(t *testing.T) {
 	event := localPlanetOccultationEventFrame{
 		label: "C2",