feat: 引入可切换星历模型并扩展天象观测链路

- 新增半解析、旧模型、自定义与多源堆叠星历实例，提供 Context、Instance、SPK 读取及状态与视位置计算
- 统一太阳、月球和行星实例接口，扩展黄经穿越、留、相位、最近角距、偕日可见、任意高度升落、轨道节点及凌日等天象查询
- 完善日月食、月掩与凌日的月缘剖面、有限盘面接触、站心修正、局地可见性、全球路径和地图输出
- 新增 SVG、GeoJSON、KML 天象输出及凌日、月掩和月缘地形相关缓存与几何求解
- 新增恒星星表导入与查询，支持 CSV、Hipparcos、BSC5、Stellarium 等格式及名称、交叉标识、锥面检索和星等过滤
- 补充 IAU 2006、地球定向、折射消光、大气观测、轨道传播及半解析行星/月球数据支持
- 将默认未来民用时标切换为 TimeScaleLeapHour，更新 2027–2400 农历速查表、中文日期解析和时区边界处理
- 增加事件基线、跨模型回归、几何边界、月缘地形和输出契约测试，完善中英文手册、示例资源、NOTICE 与忽略规则

moon/limb/limb_test.go

@@ -0,0 +1,110 @@
+package limb
+
+import (
+	"bytes"
+	"compress/zlib"
+	"crypto/sha256"
+	"encoding/binary"
+	"encoding/hex"
+	"math"
+	"testing"
+)
+
+// 内置表的 sha256；换表时须同步更新。
+const kaguyaTableSHA256 = "7d49dc75497c404b78b5b259129d0f5ab17b56522128478591ea33c8cb97d072"
+
+func TestEmbeddedTableChecksum(t *testing.T) {
+	sum := sha256.Sum256(kaguyaTable)
+	if got := hex.EncodeToString(sum[:]); got != kaguyaTableSHA256 {
+		t.Fatalf("embedded table sha256 = %s, want %s", got, kaguyaTableSHA256)
+	}
+}
+
+func TestLimbRadiusMatchesGenerator(t *testing.T) {
+	cases := []struct{ lon, lat, angle, radiusKM float64 }{
+		{0, 0, 0, 1737.432000000},
+		{3.3, -2.7, 123.45, 1735.688760000},
+		{-8.6, 7.9, 359.97, 1738.466256000},
+		{5.5, 1.25, 270.05, 1738.604000000},
+		{-1.0, -6.0, 45.0, 1737.796000000},
+	}
+	profile := Default()
+	for _, c := range cases {
+		got, ok := profile.LimbRadiusKM(c.lon, c.lat, c.angle)
+		if !ok {
+			t.Fatalf("LimbRadiusKM(%v, %v, %v) not ok", c.lon, c.lat, c.angle)
+		}
+		if math.Abs(got-c.radiusKM) > 1e-6 {
+			t.Errorf("LimbRadiusKM(%v, %v, %v) = %.9f, want %.9f", c.lon, c.lat, c.angle, got, c.radiusKM)
+		}
+	}
+}
+
+func TestLimbRadiusWrapsAndClamps(t *testing.T) {
+	profile := Default()
+	base, _ := profile.LimbRadiusKM(2, 3, 10)
+	for _, angle := range []float64{370, -350} {
+		if got, _ := profile.LimbRadiusKM(2, 3, angle); math.Abs(got-base) > 1e-9 {
+			t.Errorf("angle %v = %.9f, want %.9f", angle, got, base)
+		}
+	}
+	edge, _ := profile.LimbRadiusKM(9, -8, 10)
+	if got, _ := profile.LimbRadiusKM(12, -11, 10); got != edge {
+		t.Errorf("out-of-range libration = %.9f, want clamped %.9f", got, edge)
+	}
+	if _, ok := profile.LimbRadiusKM(math.NaN(), 0, 0); ok {
+		t.Error("NaN libration must fail")
+	}
+}
+
+func TestParseRejectsBadInput(t *testing.T) {
+	if _, err := Parse([]byte("nope")); err == nil {
+		t.Error("short input must fail")
+	}
+	broken := append([]byte(nil), kaguyaTable[:headerSize+16]...)
+	if _, err := Parse(broken); err == nil {
+		t.Error("truncated payload must fail")
+	}
+	huge := append([]byte(nil), kaguyaTable...)
+	binary.LittleEndian.PutUint32(huge[4:], 1<<30)
+	binary.LittleEndian.PutUint32(huge[8:], 1<<30)
+	if _, err := Parse(huge); err == nil {
+		t.Error("oversized header must fail before allocating")
+	}
+}
+
+func TestParseRejectsNonFiniteHeader(t *testing.T) {
+	cases := []struct {
+		name           string
+		angleStep, ref float64
+	}{
+		{name: "NaN angle step", angleStep: math.NaN(), ref: 1737.4},
+		{name: "Inf angle step", angleStep: math.Inf(1), ref: 1737.4},
+		{name: "NaN reference radius", angleStep: 180, ref: math.NaN()},
+		{name: "zero reference radius", angleStep: 180, ref: 0},
+	}
+	for _, c := range cases {
+		if _, err := Parse(syntheticTable(c.angleStep, c.ref)); err == nil {
+			t.Errorf("%s: Parse err = nil, want an error", c.name)
+		}
+	}
+	if _, err := Parse(syntheticTable(180, 1737.4)); err != nil {
+		t.Fatalf("valid header: Parse err = %v", err)
+	}
+}
+
+// syntheticTable 最小合法 2×2×2 LLB1 表，仅表头两项可变。
+func syntheticTable(angleStep, referenceRadiusKM float64) []byte {
+	var buf bytes.Buffer
+	buf.WriteString("LLB1")
+	for _, count := range []uint32{2, 2, 2} {
+		binary.Write(&buf, binary.LittleEndian, count)
+	}
+	for _, value := range []float64{0, 1, 0, 1, angleStep, referenceRadiusKM, 1} {
+		binary.Write(&buf, binary.LittleEndian, math.Float64bits(value))
+	}
+	writer := zlib.NewWriter(&buf)
+	writer.Write(make([]byte, 2*8))
+	writer.Close()
+	return buf.Bytes()
+}