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/routes/account/account.ts

@@ -1,4 +1,4 @@
-import { getAccountData, updateUser } from '@api/services/account';
+import { createViewAsStudentToken, getAccountData, updateUser } from '@api/services/account';
 
 import { Hono } from '@api/utils/hono';
 import { ZUpdateProfile } from '@cio/utils/validation/account';
@@ -51,6 +51,25 @@ export const accountRouter = new Hono()
       return handleError(c, error, 'Failed to update profile');
     }
   })
+  .post('/view-as-student-token', authMiddleware, async (c) => {
+    const user = c.get('user')!;
+
+    try {
+      // Self sign-in only — mints a login-link token for the current user so they
+      // can be auto-authenticated on the org domain to preview the student experience.
+      const token = await createViewAsStudentToken({ id: user.id, email: user.email });
+
+      return c.json(
+        {
+          success: true,
+          data: { token }
+        },
+        200
+      );
+    } catch (error) {
+      return handleError(c, error, 'Failed to create view-as-student token');
+    }
+  })
   .get('/profile', authMiddleware, async (c) => {
     const user = c.get('user')!;