fix: 兼容 TinyGo wasm 编译行星星历初始化

- 将 planetViews 从包级初始化改为 sync.Once 懒加载，避免 TinyGo interp 在编译期处理大型 float64 表切片索引时触发 unsupported fcmp
- 将行星视图构建失败改为内部返回 error，并由兼容层统一 panic
- 补充无效行星数据切片边界测试

planet/view.go

@@ -1,6 +1,9 @@
 package planet
 
-import "fmt"
+import (
+	"fmt"
+	"sync"
+)
 
 type coordSeriesView struct {
 	orders [6][]float64
@@ -11,13 +14,27 @@ type planetView struct {
 	coords [3]coordSeriesView
 }
 
-var planetViews = buildPlanetViews(planetRawData)
+var (
+	planetViewsOnce  sync.Once
+	planetViewsCache []planetView
+	planetViewsErr   error
+)
 
-func buildPlanetViews(rawData [][]float64) []planetView {
+func planetViews() []planetView {
+	planetViewsOnce.Do(func() {
+		planetViewsCache, planetViewsErr = buildPlanetViews(planetRawData)
+	})
+	if planetViewsErr != nil {
+		panic(planetViewsErr)
+	}
+	return planetViewsCache
+}
+
+func buildPlanetViews(rawData [][]float64) ([]planetView, error) {
 	views := make([]planetView, len(rawData))
 	for bodyIndex, raw := range rawData {
 		if len(raw) < 20 {
-			panic(fmt.Sprintf("planet raw data %d too short: %d", bodyIndex, len(raw)))
+			return nil, fmt.Errorf("planet raw data %d too short: %d", bodyIndex, len(raw))
 		}
 		view := planetView{scale: raw[0]}
 		for zn := 0; zn < 3; zn++ {
@@ -26,12 +43,12 @@ func buildPlanetViews(rawData [][]float64) []planetView {
 				start := int(raw[pn+order])
 				end := int(raw[pn+order+1])
 				if start < 0 || end < start || end > len(raw) {
-					panic(fmt.Sprintf("planet raw data %d coord %d order %d invalid cut: %d..%d (len=%d)", bodyIndex, zn, order, start, end, len(raw)))
+					return nil, fmt.Errorf("planet raw data %d coord %d order %d invalid cut: %d..%d (len=%d)", bodyIndex, zn, order, start, end, len(raw))
 				}
 				view.coords[zn].orders[order] = raw[start:end]
 			}
 		}
 		views[bodyIndex] = view
 	}
-	return views
+	return views, nil
 }