feat(subsonic): wire contextual_likes capture/soft-delete into star/unstar

handleStar's track branch calls playevents.CaptureContextualLikeIfPlaying
when the underlying LikeTrack actually inserted a row. handleUnstar
calls SoftDeleteContextualLikes after every track-id unstar. Same
helpers as the api surface — single source of truth.

mediaHandlers struct gains a logger field threaded through Mount.

internal/subsonic/stream.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -24,10 +25,11 @@ import (
 type mediaHandlers struct {
 	pool   *pgxpool.Pool
 	events *playevents.Writer
+	logger *slog.Logger
 }
 
-func newMediaHandlers(pool *pgxpool.Pool, events *playevents.Writer) *mediaHandlers {
-	return &mediaHandlers{pool: pool, events: events}
+func newMediaHandlers(pool *pgxpool.Pool, events *playevents.Writer, logger *slog.Logger) *mediaHandlers {
+	return &mediaHandlers{pool: pool, events: events, logger: logger}
 }
 
 // handleStream serves the raw track bytes. http.ServeContent gives us Range,