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/ui/powered-by.svelte

@@ -2,6 +2,7 @@
   import ArrowUpRightIcon from '@lucide/svelte/icons/arrow-up-right';
 
   import { PublicCoursePoweredBy } from '@cio/ui/custom/public-course';
+  import { TENANT_ROOT_DOMAIN } from '@cio/utils/constants/domains';
   import { t } from '$lib/utils/functions/translations';
   import { currentOrg, isFreePlan } from '$lib/utils/store/org';
   import { cn } from '@cio/ui/tools';
@@ -44,7 +45,7 @@
   />
 {:else if $isFreePlan}
   <a
-    href={`https://classroomio.com?utm_source=${$currentOrg.siteName}.classroomio.com`}
+    href={`https://classroomio.com?utm_source=${$currentOrg.siteName}.${TENANT_ROOT_DOMAIN}`}
     target="_blank"
     class={cn('group fixed right-9 bottom-14 z-50 hover:no-underline', className)}
   >