Add per-disk profiles with video transcoding support

Each disk stores .jukebox/profile.json with copy parameters (dest
folder, overwrite mode, file select, reserve space, auto-copy) and
optional transcoding limits for the target player (codec, resolution,
bitrate, FPS, audio channels, output format).

On copy, video files are probed with ffprobe; if they exceed the
profile limits they are transcoded via ffmpeg (-threads 0 for full
CPU usage), otherwise copied as-is. Scale filter never upscales.

New: internal/disk/profile.go, internal/transcoder/{detect,transcoder}.go
API: GET/PUT /api/disks/profile?mount_path=
UI: disk profile panel in dashboard for known disks
Dockerfile: adds ffmpeg to the runtime image

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

internal/api/handlers_disk.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"time"
 
+	"jukebox_maker/internal/config"
 	"jukebox_maker/internal/disk"
 )
 
@@ -15,6 +16,7 @@ func (s *Server) diskResponse(info disk.DiskInfo) map[string]any {
 		"total_bytes": info.TotalBytes,
 		"free_bytes":  info.FreeBytes,
 		"mount_path":  info.MountPath,
+		"profile":     info.Profile,
 	}
 	if info.DiskID != "" {
 		if s.deps.OnDiskInit != nil {
@@ -113,3 +115,39 @@ func (s *Server) handleDiskInit(w http.ResponseWriter, r *http.Request) {
 	}
 	jsonOK(w, map[string]string{"disk_id": diskID})
 }
+
+func (s *Server) handleGetProfile(w http.ResponseWriter, r *http.Request) {
+	mountPath := config.NormalizeMediaPath(r.URL.Query().Get("mount_path"))
+	if mountPath == "" {
+		jsonErr(w, http.StatusBadRequest, "mount_path is required")
+		return
+	}
+	p, err := disk.LoadProfile(mountPath)
+	if err != nil {
+		jsonErr(w, http.StatusNotFound, "profile not found")
+		return
+	}
+	jsonOK(w, p)
+}
+
+func (s *Server) handlePutProfile(w http.ResponseWriter, r *http.Request) {
+	mountPath := config.NormalizeMediaPath(r.URL.Query().Get("mount_path"))
+	if mountPath == "" {
+		jsonErr(w, http.StatusBadRequest, "mount_path is required")
+		return
+	}
+	var p disk.DiskProfile
+	if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
+		jsonErr(w, http.StatusBadRequest, "invalid JSON: "+err.Error())
+		return
+	}
+	if err := disk.SaveProfile(mountPath, &p); err != nil {
+		jsonErr(w, http.StatusInternalServerError, "save profile: "+err.Error())
+		return
+	}
+	// Обновляем информацию о диске в watcher если он там есть
+	if s.deps.Watcher != nil {
+		s.deps.Watcher.ProbeNow()
+	}
+	jsonOK(w, &p)
+}