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/ui/src/custom/org-landing-page/tech/index.ts

@@ -0,0 +1,8 @@
+export { default as nav } from './nav.svelte';
+export { default as hero } from './hero.svelte';
+export { default as courseCard } from './course-card.svelte';
+export { default as org } from './org.svelte';
+export { default as course } from './course.svelte';
+
+export const coursesGridClass =
+  'ui:grid ui:grid-cols-1 ui:@xl:grid-cols-2 ui:@4xl:grid-cols-3 ui:border-t ui:border-l ui:border-[var(--landing-border)]';