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/api/src/__tests__/course-go-live-readiness.test.ts

@@ -4,13 +4,13 @@ import { getCourseById } from '@cio/db/queries/course';
 import { getCourseContentItems, type CourseContentItemRow } from '@cio/db/queries/course/content';
 import { getCourseOrganizationId } from '@cio/db/queries/tag';
 import { getOrganizationById } from '@cio/db/queries/organization';
-import { updateCourse } from '../services/course/course';
-import { ensureCourseSlug, generateUniqueCourseSlug } from '../services/course/landing-page';
+import { updateCourse } from '@cio/core/services/course/course';
+import { ensureCourseSlug, generateUniqueCourseSlug } from '@cio/core/services/course/landing-page';
 import {
   evaluateCourseGoLiveReadiness,
   getCourseGoLiveReadiness,
   publishCourseWhenReady
-} from '../services/course/go-live-readiness';
+} from '@cio/core/services/course/go-live-readiness';
 
 vi.mock('@cio/db/queries/course', () => ({
   getCourseById: vi.fn()
@@ -28,16 +28,19 @@ vi.mock('@cio/db/queries/organization', () => ({
   getOrganizationById: vi.fn()
 }));
 
-vi.mock('../services/course/course', () => ({
+vi.mock('@cio/core/services/course/course', () => ({
   updateCourse: vi.fn()
 }));
 
-vi.mock('../services/course/landing-page', () => ({
-  buildCourseBaseUrl: vi.fn(() => 'https://school.example.com'),
+vi.mock('@cio/core/services/course/landing-page', () => ({
   ensureCourseSlug: vi.fn(),
   generateUniqueCourseSlug: vi.fn()
 }));
 
+vi.mock('@cio/core/config/dashboard-url', () => ({
+  getDashboardBaseUrl: vi.fn(() => 'https://school.example.com')
+}));
+
 const mockedGetCourseById = vi.mocked(getCourseById);
 const mockedGetCourseContentItems = vi.mocked(getCourseContentItems);
 const mockedGetCourseOrganizationId = vi.mocked(getCourseOrganizationId);