feat: add durable schedule management and multi-node crash recovery

internal/timezone/zone.go

@@ -0,0 +1,61 @@
+// Package timezone 提供随计划冻结的时区快照，禁止读取宿主机或 ZONEINFO 环境配置。
+package timezone
+
+import (
+	"archive/zip"
+	"bytes"
+	_ "embed"
+	"errors"
+	"io"
+	"sync"
+	"time"
+)
+
+// Version 标识 Go 1.27.1 附带的 IANA 快照及文件摘要；升级时须保留旧版本可读能力。
+const Version = "go1.27.1-b2d18a7c8fa8"
+
+//go:embed zoneinfo.zip
+var data []byte
+var zones sync.Map
+var archive = sync.OnceValues(func() (*zip.Reader, error) { return zip.NewReader(bytes.NewReader(data), int64(len(data))) })
+
+// Load 仅接受精确的内置名称，返回只读 Location；不接受 Local 或文件系统路径。
+func Load(name, version string) (*time.Location, error) {
+	if version != Version || name == "" || name == "Local" || len(name) > 64 {
+		return nil, errors.New("unsupported frozen timezone version or name")
+	}
+	if name == "UTC" {
+		return time.UTC, nil
+	}
+	if v, ok := zones.Load(name); ok {
+		return v.(*time.Location), nil
+	}
+	a, err := archive()
+	if err != nil {
+		return nil, err
+	}
+	for _, entry := range a.File {
+		if entry.Name != name {
+			continue
+		}
+		r, err := entry.Open()
+		if err != nil {
+			return nil, err
+		}
+		b, err := io.ReadAll(io.LimitReader(r, 1<<20))
+		closeErr := r.Close()
+		if err != nil {
+			return nil, err
+		}
+		if closeErr != nil {
+			return nil, closeErr
+		}
+		loc, err := time.LoadLocationFromTZData(name, b)
+		if err != nil {
+			return nil, err
+		}
+		actual, _ := zones.LoadOrStore(name, loc)
+		return actual.(*time.Location), nil
+	}
+	return nil, errors.New("unknown IANA timezone")
+}