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

apps/dashboard/src/lib/features/widget/utils/layout-thumbnail.ts

@@ -1,7 +1,7 @@
 import type { TWidgetLayoutType } from '@cio/utils/validation/widget';
 
-/** Served from `apps/dashboard/static/templates/widget-layouts/*.png` (~720px max edge for sharp downscaling). */
-export const WIDGET_LAYOUT_THUMBNAIL_BASE = '/templates/widget-layouts';
+/** Served from CDN. */
+export const WIDGET_LAYOUT_THUMBNAIL_BASE = 'https://assets.cdn.clsrio.com/templates/widget-layouts';
 
 export function widgetLayoutThumbnailSrc(layoutType: TWidgetLayoutType): string {
   return `${WIDGET_LAYOUT_THUMBNAIL_BASE}/${layoutType}.png`;