feat: add multi-user support for favorites management and room clock synchronization

- Implemented a new API endpoint for retrieving and managing user favorites in /api/users.
- Added functionality for admins to edit the shared "main" user's favorites.
- Created a one-shot DB smoke test script for verifying multi-user kiosk migrations.
- Introduced a RoomClock class for synchronizing server time across clients using WebSocket.

server/db/index.js

@@ -71,5 +71,25 @@ function runMigrations(db) {
     if (!playCols.has('total_play_ms')) {
         db.exec('ALTER TABLE station_plays ADD COLUMN total_play_ms INTEGER NOT NULL DEFAULT 0');
     }
+
+    // Multi-user kiosk: per-user metadata + designation of "main" identity.
+    const userCols = new Set(db.prepare("PRAGMA table_info(users)").all().map((c) => c.name));
+    if (!userCols.has('is_main')) {
+        db.exec('ALTER TABLE users ADD COLUMN is_main INTEGER NOT NULL DEFAULT 0');
+    }
+    if (!userCols.has('avatar_color')) {
+        db.exec('ALTER TABLE users ADD COLUMN avatar_color TEXT');
+    }
+    if (!userCols.has('avatar_emoji')) {
+        db.exec('ALTER TABLE users ADD COLUMN avatar_emoji TEXT');
+    }
+    db.exec('CREATE UNIQUE INDEX IF NOT EXISTS idx_users_only_one_main ON users(is_main) WHERE is_main = 1');
+
+    // Cross-client stream sync: when a room enters 'play', record the wall-clock
+    // moment so every client can target the same playhead.
+    const stateCols = new Set(db.prepare("PRAGMA table_info(room_state)").all().map((c) => c.name));
+    if (!stateCols.has('started_at')) {
+        db.exec('ALTER TABLE room_state ADD COLUMN started_at INTEGER');
+    }
 }
 

server/db/schema.sql

@@ -3,8 +3,30 @@ CREATE TABLE IF NOT EXISTS users (
   username      TEXT NOT NULL UNIQUE,
   password_hash TEXT NOT NULL,
   role          TEXT NOT NULL DEFAULT 'user' CHECK (role IN ('admin','user')),
+  is_main       INTEGER NOT NULL DEFAULT 0,         -- exactly one user is the shared "main" identity
+  avatar_color  TEXT,                                -- cosmetic, used by avatar picker
+  avatar_emoji  TEXT,                                -- cosmetic, used by avatar picker
   created_at    TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
+-- Note: the partial unique index on users(is_main) is created by runMigrations()
+-- after legacy DBs have the is_main column added via ALTER TABLE.
+
+-- Trusted kiosk/browser devices. A device cookie (random token) is set after
+-- an admin marks the device trusted. Users on the device's whitelist can
+-- fast-switch without re-entering a password.
+CREATE TABLE IF NOT EXISTS kiosk_devices (
+  id           INTEGER PRIMARY KEY AUTOINCREMENT,
+  token        TEXT NOT NULL UNIQUE,
+  label        TEXT,
+  created_at   TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  last_seen_at TEXT
+);
+CREATE TABLE IF NOT EXISTS kiosk_device_users (
+  device_id INTEGER NOT NULL REFERENCES kiosk_devices(id) ON DELETE CASCADE,
+  user_id   INTEGER NOT NULL REFERENCES users(id)         ON DELETE CASCADE,
+  PRIMARY KEY (device_id, user_id)
+);
+CREATE INDEX IF NOT EXISTS idx_kiosk_device_users_user ON kiosk_device_users(user_id);
 
 CREATE TABLE IF NOT EXISTS sessions (
   token      TEXT PRIMARY KEY,
@@ -132,6 +154,7 @@ CREATE TABLE IF NOT EXISTS room_state (
   station_id INTEGER REFERENCES stations(id) ON DELETE SET NULL,
   playing    INTEGER NOT NULL DEFAULT 0,
   volume     REAL NOT NULL DEFAULT 0.7,
+  started_at INTEGER,                          -- epoch ms when playback (or current station) began; anchors cross-client sync
   updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
 );