feat(media): add phase5 media provider abstraction and stream credentials APIs

Backend/utils/stream-token.ts

@@ -1,31 +0,0 @@
-import { createHmac } from 'crypto';
-
-type StreamPlaybackPayload = {
-  sessionId: string;
-  viewerDeviceId: string;
-  userId: string;
-  exp: number;
-};
-
-const secret = process.env.BETTER_AUTH_SECRET;
-
-if (!secret) {
-  throw new Error('BETTER_AUTH_SECRET is required for stream playback token signing');
-}
-
-const sign = (data: string): string => createHmac('sha256', secret).update(data).digest('base64url');
-
-export const createStreamPlaybackToken = (
-  payload: Omit<StreamPlaybackPayload, 'exp'>,
-  ttlSeconds = 60 * 15,
-): string => {
-  const body: StreamPlaybackPayload = {
-    ...payload,
-    exp: Math.floor(Date.now() / 1000) + ttlSeconds,
-  };
-
-  const encodedPayload = Buffer.from(JSON.stringify(body), 'utf8').toString('base64url');
-  const signature = sign(encodedPayload);
-
-  return `${encodedPayload}.${signature}`;
-};