feat: HLS streaming, transcripts, agent course generation & landing-page course previews (#663)

New features:
- HLS video encoding/streaming (hls routes, hls-encoder) and a media
  transcripts pipeline (transcripts route + media-transcript queries)
- AI assistant chat vs. run model: agent-course-generation worker/queue,
  run-monitor pane, chat-changes card, content ask-ai bar
- Per-theme course-page previews across org landing-page themes (bold,
  classic, corporate, editorial, etc.) with a shared course token/component set
- View-as-student mode and login-link / link-invite invite flows

Refactor:
- Extract packages/core consolidating config (env, storage, dashboard-url),
  services and utils previously duplicated under apps/api/src/config
- Remove legacy agent service modules (chat-tools, chat-context,
  context-window, document, fetch-url, lesson-content)
- Relax Cross-Origin-Resource-Policy to allow cross-origin media embedding
- Add format script to tenant-router so turbo run format covers it

packages/core/src/utils/redis/redis.ts

@@ -0,0 +1,57 @@
+import { createClient, type RedisClientType } from 'redis';
+import { env } from '../../config/env';
+
+// Create Redis client
+const client: RedisClientType = createClient({
+  url: env.REDIS_URL
+});
+
+let hasLoggedRedisUnavailable = false;
+
+export function logRedisUnavailableOnce(message: string, error?: unknown): void {
+  if (hasLoggedRedisUnavailable) {
+    return;
+  }
+
+  hasLoggedRedisUnavailable = true;
+
+  if (error) {
+    console.warn(message, error);
+    return;
+  }
+
+  console.warn(message);
+}
+
+// Handle connection events
+client.on('error', (err) => {
+  logRedisUnavailableOnce('Redis unavailable, Redis-backed features disabled', err);
+});
+
+client.on('connect', () => {
+  console.log('Redis Client Connected');
+});
+
+// Track connection state
+let isConnected = false;
+
+export async function connectRedis(): Promise<void> {
+  if (!env.REDIS_URL) {
+    logRedisUnavailableOnce('REDIS_URL not set, Redis features disabled');
+    return;
+  }
+  if (isConnected) return;
+  try {
+    await client.connect();
+    isConnected = true;
+  } catch (error) {
+    logRedisUnavailableOnce('Redis connection failed, API will run without Redis', error);
+    // Don't throw - allow API to start; rate limiting and caching will degrade gracefully
+  }
+}
+
+// Export the client (connection will be established before server starts)
+export const redis: RedisClientType = client;
+
+// Export type for use in other files
+export type RedisClient = RedisClientType;