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/api/handlers_disk.go

@@ -0,0 +1,34 @@
+package api
+
+import (
+	"net/http"
+
+	"jukebox_maker/internal/disk"
+)
+
+func (s *Server) handleDiskStatus(w http.ResponseWriter, r *http.Request) {
+	info := s.deps.Watcher.CurrentDisk()
+
+	type response struct {
+		State        disk.DiskState `json:"state"`
+		DiskID       string         `json:"disk_id"`
+		TotalBytes   int64          `json:"total_bytes"`
+		FreeBytes    int64          `json:"free_bytes"`
+		MountPath    string         `json:"mount_path"`
+		ActiveTaskID string         `json:"active_task_id,omitempty"`
+	}
+
+	resp := response{
+		State:      info.State,
+		DiskID:     info.DiskID,
+		TotalBytes: info.TotalBytes,
+		FreeBytes:  info.FreeBytes,
+		MountPath:  info.MountPath,
+	}
+
+	if t, ok := s.deps.Tasks.ActiveTask(); ok {
+		resp.ActiveTaskID = t.ID
+	}
+
+	jsonOK(w, resp)
+}