sfu-signaling: real Janus signaling service implementation

- JanusClient.php: HTTP REST client for Janus Gateway API
- SfuRoomRepository.php: room + participant + stats persistence
- bootstrap.php: PDO, auth, Janus client factory
- public/index.php: front-controller routing
- public/health.php: Janus online check
- public/api/rooms.php: list/create/destroy rooms
- public/api/join.php: SDP offer relay → Janus VideoRoom
- public/api/stats.php: bitrate/packet-loss analytics ingest
- public/dashboard.php: SFU rooms UI (common BE dark-theme styles)

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

src/bootstrap.php

@@ -0,0 +1,119 @@
+<?php
+declare(strict_types=1);
+
+/*
+ * SFU signaling bootstrap — minimal standalone setup.
+ * Reuses the composed BE database and session if available,
+ * otherwise falls back to own PDO from environment.
+ */
+
+define('SFU_ROOT', dirname(__DIR__));
+
+/* ── autoloader ───────────────────────────────────────────────────── */
+spl_autoload_register(static function (string $class): void {
+    $prefix = 'AndroidCast\\Sfu\\';
+    if (str_starts_with($class, $prefix)) {
+        $rel  = str_replace('\\', '/', substr($class, strlen($prefix)));
+        $file = SFU_ROOT . '/src/' . $rel . '.php';
+        if (is_file($file)) {
+            require_once $file;
+        }
+    }
+});
+
+/* ── configuration ────────────────────────────────────────────────── */
+
+function sfuConfig(string $key, mixed $default = null): mixed
+{
+    static $cfg = null;
+    if ($cfg === null) {
+        $cfgFile = SFU_ROOT . '/config/config.php';
+        $cfg = is_file($cfgFile) ? (require $cfgFile) : [];
+        /* Env overrides */
+        if (getenv('JANUS_URL') !== false) {
+            $cfg['janus_url'] = getenv('JANUS_URL');
+        }
+        if (getenv('DB_DSN') !== false) {
+            $cfg['db_dsn'] = getenv('DB_DSN');
+        }
+    }
+    return $cfg[$key] ?? $default;
+}
+
+/* ── PDO ────────────────────────────────────────────────────────────── */
+
+function sfuPdo(): \PDO
+{
+    static $pdo = null;
+    if ($pdo === null) {
+        /* Prefer composed BE PDO if already bootstrapped */
+        $composedBe = '/var/www/ac/composed/backend/src/bootstrap.php';
+        if (is_file($composedBe)) {
+            require_once $composedBe;
+            if (function_exists('db')) {
+                $pdo = db();
+                return $pdo;
+            }
+        }
+        /* Fall back to own DSN */
+        $dsn  = sfuConfig('db_dsn', 'mysql:host=cast01;dbname=androidcast;charset=utf8mb4');
+        $user = sfuConfig('db_user', 'androidcast');
+        $pass = sfuConfig('db_pass', '');
+        $pdo  = new \PDO($dsn, $user, $pass, [
+            \PDO::ATTR_ERRMODE            => \PDO::ERRMODE_EXCEPTION,
+            \PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC,
+        ]);
+    }
+    return $pdo;
+}
+
+/* ── Janus client ────────────────────────────────────────────────── */
+
+function janusClient(): \AndroidCast\Sfu\JanusClient
+{
+    static $client = null;
+    if ($client === null) {
+        $url    = sfuConfig('janus_url', 'http://10.7.16.237:8088/janus');
+        $client = new \AndroidCast\Sfu\JanusClient($url);
+    }
+    return $client;
+}
+
+/* ── Auth helper ─────────────────────────────────────────────────── */
+
+function sfuRequireAuth(): array
+{
+    /* Try composed BE session */
+    $composedBe = '/var/www/ac/composed/backend/src/bootstrap.php';
+    if (is_file($composedBe)) {
+        require_once $composedBe;
+        if (function_exists('requireAuth')) {
+            return requireAuth();
+        }
+    }
+    /* Minimal cookie/bearer check */
+    session_start();
+    if (empty($_SESSION['user_id'])) {
+        http_response_code(401);
+        echo json_encode(['ok' => false, 'error' => 'unauthorized']);
+        exit;
+    }
+    return ['id' => (int) $_SESSION['user_id'], 'email' => $_SESSION['email'] ?? ''];
+}
+
+/* ── JSON helpers ────────────────────────────────────────────────── */
+
+function sfuJsonOk(array $data = []): void
+{
+    header('Content-Type: application/json; charset=utf-8');
+    echo json_encode(['ok' => true] + $data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
+    exit;
+}
+
+function sfuJsonErr(string $message, int $code = 400): void
+{
+    http_response_code($code);
+    header('Content-Type: application/json; charset=utf-8');
+    echo json_encode(['ok' => false, 'error' => $message], JSON_UNESCAPED_SLASHES);
+    exit;
+}