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_config.go

@@ -0,0 +1,41 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+	"sync"
+
+	"jukebox_maker/internal/config"
+)
+
+var cfgMu sync.Mutex
+
+func (s *Server) handleGetConfig(w http.ResponseWriter, r *http.Request) {
+	cfgMu.Lock()
+	cfg := *s.deps.Config
+	cfgMu.Unlock()
+	jsonOK(w, cfg)
+}
+
+func (s *Server) handlePutConfig(w http.ResponseWriter, r *http.Request) {
+	var incoming config.Config
+	if err := json.NewDecoder(r.Body).Decode(&incoming); err != nil {
+		jsonErr(w, http.StatusBadRequest, "invalid JSON: "+err.Error())
+		return
+	}
+	if err := incoming.Validate(); err != nil {
+		jsonErr(w, http.StatusUnprocessableEntity, err.Error())
+		return
+	}
+
+	cfgMu.Lock()
+	*s.deps.Config = incoming
+	cfgMu.Unlock()
+
+	if err := config.Save(s.deps.ConfigPath, s.deps.Config); err != nil {
+		jsonErr(w, http.StatusInternalServerError, "failed to save config: "+err.Error())
+		return
+	}
+
+	jsonOK(w, incoming)
+}