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/core/src/index.ts

@@ -0,0 +1,13 @@
+/**
+ * Public surface of `@cio/core`.
+ *
+ * Most consumers reach into the package via subpath imports (`./services/*`,
+ * `./utils/*`, `./config/*` — see `package.json` exports). The top-level
+ * surface is intentionally narrow: it only re-exports the durable agent
+ * runner used by the BullMQ worker in `apps/jobs`.
+ */
+
+export {
+  runAgentCourseGenerationJob,
+  type RunAgentCourseGenerationJobInput
+} from './services/agent/course-generation-runner';