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/migrations/00005_playback.sql

@@ -0,0 +1,86 @@
+-- +goose Up
+CREATE TYPE reaction AS ENUM ('like', 'dislike');
+
+CREATE TABLE track_reactions (
+  user_id    uuid REFERENCES users(id) ON DELETE CASCADE,
+  track_id   uuid REFERENCES tracks(id) ON DELETE CASCADE,
+  reaction   reaction NOT NULL,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY (user_id, track_id)
+);
+CREATE INDEX track_reactions_list_idx ON track_reactions (user_id, reaction, created_at DESC);
+
+CREATE TABLE artist_reactions (
+  user_id    uuid REFERENCES users(id) ON DELETE CASCADE,
+  artist_id  uuid REFERENCES artists(id) ON DELETE CASCADE,
+  reaction   reaction NOT NULL,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY (user_id, artist_id)
+);
+
+-- Сырые события. Помесячные партиции добавим, когда объём того потребует; пока всё в DEFAULT.
+CREATE TABLE play_events (
+  id              uuid NOT NULL,
+  user_id         uuid NOT NULL,
+  track_id        uuid NOT NULL,
+  type            text NOT NULL,
+  occurred_at     timestamptz NOT NULL,
+  received_at     timestamptz NOT NULL DEFAULT now(),
+  position_ms     int,
+  played_ms       int,
+  context_type    text,
+  context_id      text,
+  wave_session_id uuid,
+  client_type     text NOT NULL,
+  offline         boolean NOT NULL DEFAULT false,
+  PRIMARY KEY (id, occurred_at)
+) PARTITION BY RANGE (occurred_at);
+CREATE TABLE play_events_default PARTITION OF play_events DEFAULT;
+CREATE INDEX play_events_user_idx ON play_events (user_id, occurred_at DESC);
+
+CREATE TABLE user_track_stats (
+  user_id          uuid REFERENCES users(id) ON DELETE CASCADE,
+  track_id         uuid REFERENCES tracks(id) ON DELETE CASCADE,
+  play_count       int NOT NULL DEFAULT 0,
+  complete_count   int NOT NULL DEFAULT 0,
+  skip_count       int NOT NULL DEFAULT 0,
+  early_skip_count int NOT NULL DEFAULT 0,
+  total_played_ms  bigint NOT NULL DEFAULT 0,
+  last_played_at   timestamptz,
+  implicit_score   real NOT NULL DEFAULT 0,
+  PRIMARY KEY (user_id, track_id)
+);
+
+-- История: по строке на прослушивание ≥ 30 с (или коротких треков целиком). id — id события.
+CREATE TABLE listen_history (
+  id        uuid PRIMARY KEY,
+  user_id   uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  track_id  uuid NOT NULL REFERENCES tracks(id) ON DELETE CASCADE,
+  played_at timestamptz NOT NULL,
+  played_ms int NOT NULL,
+  hidden    boolean NOT NULL DEFAULT false
+);
+CREATE INDEX listen_history_user_idx ON listen_history (user_id, played_at DESC, id DESC) WHERE NOT hidden;
+
+CREATE TABLE playback_state (
+  user_id     uuid PRIMARY KEY REFERENCES users(id) ON DELETE CASCADE,
+  track_id    uuid REFERENCES tracks(id) ON DELETE SET NULL,
+  position_ms int NOT NULL DEFAULT 0,
+  queue       jsonb NOT NULL DEFAULT '[]',
+  queue_index int NOT NULL DEFAULT 0,
+  context     jsonb,
+  shuffle     boolean NOT NULL DEFAULT false,
+  repeat_mode text NOT NULL DEFAULT 'off',
+  volume      real NOT NULL DEFAULT 1,
+  device_id   text,
+  updated_at  timestamptz NOT NULL DEFAULT now()
+);
+
+-- +goose Down
+DROP TABLE playback_state;
+DROP TABLE listen_history;
+DROP TABLE user_track_stats;
+DROP TABLE play_events;
+DROP TABLE artist_reactions;
+DROP TABLE track_reactions;
+DROP TYPE reaction;