Add jukebox_maker web app v1.0

Go web application for filling USB drives with media files.
Runs in Docker on Unraid with /media, /mnt/usb, /config volumes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/disk/disk.go

@@ -0,0 +1,88 @@
+package disk
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/google/uuid"
+)
+
+type DiskState string
+
+const (
+	DiskAbsent  DiskState = "absent"
+	DiskForeign DiskState = "foreign"
+	DiskKnown   DiskState = "known"
+)
+
+type DiskInfo struct {
+	State      DiskState `json:"state"`
+	DiskID     string    `json:"disk_id"`
+	TotalBytes int64     `json:"total_bytes"`
+	FreeBytes  int64     `json:"free_bytes"`
+	MountPath  string    `json:"mount_path"`
+}
+
+const markerDir = ".jukebox"
+const idFile = "disk.id"
+
+func Probe(mountPath string) (DiskInfo, error) {
+	info := DiskInfo{MountPath: mountPath, State: DiskAbsent}
+
+	entries, err := os.ReadDir(mountPath)
+	if err != nil || len(entries) == 0 {
+		return info, nil
+	}
+
+	total, free, err := DiskUsage(mountPath)
+	if err != nil {
+		return info, nil
+	}
+	info.TotalBytes = total
+	info.FreeBytes = free
+
+	idPath := filepath.Join(mountPath, markerDir, idFile)
+	data, err := os.ReadFile(idPath)
+	if errors.Is(err, os.ErrNotExist) {
+		info.State = DiskForeign
+		return info, nil
+	}
+	if err != nil {
+		info.State = DiskForeign
+		return info, nil
+	}
+
+	info.DiskID = strings.TrimSpace(string(data))
+	info.State = DiskKnown
+	return info, nil
+}
+
+func InitDisk(mountPath string) (string, error) {
+	dir := filepath.Join(mountPath, markerDir)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return "", err
+	}
+	id := uuid.New().String()
+	idPath := filepath.Join(dir, idFile)
+	if err := os.WriteFile(idPath, []byte(id), 0o644); err != nil {
+		return "", err
+	}
+	return id, nil
+}
+
+func DBPath(mountPath string) string {
+	return filepath.Join(mountPath, markerDir, "history.db")
+}
+
+func DiskUsage(mountPath string) (total, free int64, err error) {
+	var stat syscall.Statfs_t
+	if err = syscall.Statfs(mountPath, &stat); err != nil {
+		return 0, 0, err
+	}
+	total = int64(stat.Blocks) * int64(stat.Bsize)
+	free = int64(stat.Bavail) * int64(stat.Bsize)
+	return total, free, nil
+}