feat(api): streaming, transcoding, events, history and likes (M3)

- tracks carry a stream_url signed for the user for 12 h and the
  user's reaction; /stream checks the signature, expiry and that the
  user is not blocked, then hands the file to nginx by X-Accel-Redirect
  (or serves it with Range support when X_ACCEL=false)
- original by default; formats browsers can't play and explicit
  high/medium/low go through Opus transcoding, never upwards: a lossy
  source under the target bitrate stays original; transcodes are
  cached per file and size, deduplicated in flight, limited by
  TRANSCODE_CONCURRENCY and trimmed hourly by LRU to the size limit
- /events takes up to 500 events with client UUIDs, drops repeats and
  events older than 30 days, counts plays (≥ half or 4 min, or
  finished), early skips and history entries (≥ 30 s)
- history with clearing, likes and dislikes with cursors and totals,
  track reactions, playback state with last-write-wins, tracks batch

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/internal/library/handler.go

@@ -28,12 +28,35 @@ type Handler struct {
 }
 
 // NewHandler создаёт обработчик.
-func NewHandler(svc *Service, store *Store, signer *sign.Signer, covers *Covers, xAccel bool) *Handler {
-	return &Handler{DTO: DTO{Signer: signer}, svc: svc, store: store, covers: covers, xAccel: xAccel}
+func NewHandler(svc *Service, store *Store, dto DTO, covers *Covers, xAccel bool) *Handler {
+	return &Handler{DTO: dto, svc: svc, store: store, covers: covers, xAccel: xAccel}
 }
 
 // DTO переводит строки каталога в схемы API; подписывает ссылки на обложки.
-type DTO struct{ Signer *sign.Signer }
+type DTO struct {
+	Signer *sign.Signer
+	// Personal дополняет треки данными текущего пользователя (ссылка на стрим, реакция).
+	Personal Personalizer
+}
+
+// Personalizer заполняет персональные поля треков для пользователя из контекста запроса.
+type Personalizer interface {
+	Personalize(ctx context.Context, rows []TrackRow, out []gen.Track) error
+}
+
+// Tracks переводит треки в схему и добавляет персональные поля.
+func (d DTO) Tracks(ctx context.Context, rows []TrackRow) ([]gen.Track, error) {
+	out := make([]gen.Track, 0, len(rows))
+	for _, t := range rows {
+		out = append(out, d.Track(t))
+	}
+	if d.Personal != nil && len(out) > 0 {
+		if err := d.Personal.Personalize(ctx, rows, out); err != nil {
+			return nil, err
+		}
+	}
+	return out, nil
+}
 
 func (h *Handler) sourceDTO(s Source) gen.Source {
 	out := gen.Source{
@@ -382,11 +405,13 @@ func (h *Handler) GetAlbum(ctx context.Context, req gen.GetAlbumRequestObject) (
 	}
 	out := gen.GetAlbum200JSONResponse{
 		Id: a.ID, Title: a.Title, Year: a.Year, CoverUrl: h.coverURL(a), CoverColors: colors(a.CoverColors),
-		Artist: gen.ArtistRef{Id: a.Artist.ID, Name: a.Artist.Name}, Tracks: make([]gen.Track, 0, len(tracks)),
+		Artist: gen.ArtistRef{Id: a.Artist.ID, Name: a.Artist.Name},
 	}
 	for _, t := range tracks {
 		out.DurationMs += t.DurationMs
-		out.Tracks = append(out.Tracks, h.Track(t))
+	}
+	if out.Tracks, err = h.Tracks(ctx, tracks); err != nil {
+		return nil, err
 	}
 	return out, nil
 }
@@ -397,7 +422,11 @@ func (h *Handler) GetTrack(ctx context.Context, req gen.GetTrackRequestObject) (
 	if err != nil {
 		return nil, catalogErr(err)
 	}
-	return gen.GetTrack200JSONResponse(h.Track(t)), nil
+	dto, err := h.Tracks(ctx, []TrackRow{t})
+	if err != nil {
+		return nil, err
+	}
+	return gen.GetTrack200JSONResponse(dto[0]), nil
 }
 
 // GetCover реализует gen.StrictServerInterface: проверяет подпись и отдаёт WebP нужного размера.