feat: add personal playlists and shareable track links

EOF

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/data-model.md

@@ -41,7 +41,7 @@ CREATE TABLE refresh_tokens (
   family_started_at timestamptz NOT NULL,    -- время входа: абсолютный срок семьи (180 дней)
   token_hash   bytea NOT NULL UNIQUE,        -- SHA-256 от токена
   device_name  text,                         -- "Chrome / Windows", "Pixel 8"
-  client_type  text NOT NULL,                -- 'web' | 'android'
+  client_type  text NOT NULL,                -- 'web' | 'android' | 'desktop'
   created_at   timestamptz NOT NULL DEFAULT now(),
   expires_at   timestamptz NOT NULL,
   used_at      timestamptz,                  -- ротирован
@@ -303,6 +303,25 @@ CREATE TABLE track_reactions (             -- Коллекция → Лайки
 );
 CREATE INDEX ON track_reactions (user_id, reaction, created_at DESC);
 
+CREATE TABLE playlists (
+  id          uuid PRIMARY KEY,
+  user_id     uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  name        text NOT NULL CHECK (char_length(name) BETWEEN 1 AND 120),
+  description text NOT NULL DEFAULT '' CHECK (char_length(description) <= 2000),
+  revision    integer NOT NULL DEFAULT 1,  -- оптимистичная блокировка при PUT
+  created_at  timestamptz NOT NULL DEFAULT now(),
+  updated_at  timestamptz NOT NULL DEFAULT now()
+);
+CREATE INDEX playlists_owner ON playlists(user_id, updated_at DESC, id);
+
+CREATE TABLE playlist_tracks (
+  playlist_id uuid NOT NULL REFERENCES playlists(id) ON DELETE CASCADE,
+  track_id    uuid NOT NULL REFERENCES tracks(id) ON DELETE CASCADE,
+  position    integer NOT NULL CHECK (position >= 0),
+  PRIMARY KEY (playlist_id, track_id),
+  UNIQUE (playlist_id, position)
+);
+
 CREATE TABLE artist_reactions (            -- «не рекомендовать исполнителя» и т.п.
   user_id uuid REFERENCES users(id) ON DELETE CASCADE,
   artist_id uuid REFERENCES artists(id) ON DELETE CASCADE,
@@ -324,7 +343,7 @@ CREATE TABLE play_events (
   context_type  text,                      -- wave | album | artist | search | collection | history | queue
   context_id    text,                      -- id альбома / wave_session и т.п.
   wave_session_id uuid,
-  client_type   text NOT NULL,             -- web | android
+  client_type   text NOT NULL,             -- web | android | desktop
   offline       boolean NOT NULL DEFAULT false,
   PRIMARY KEY (id, occurred_at)
 ) PARTITION BY RANGE (occurred_at);