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/base/dialog/dialog-content.svelte

@@ -25,7 +25,11 @@
     bind:ref
     data-slot="dialog-content"
     class={cn(
-      'ui:bg-background ui:border ui:data-[state=open]:animate-in ui:data-[state=closed]:animate-out ui:data-[state=closed]:fade-out-0 ui:data-[state=open]:fade-in-0 ui:data-[state=closed]:zoom-out-95 ui:data-[state=open]:zoom-in-95 ui:fixed ui:left-[50%] ui:top-[50%] ui:z-200 ui:grid ui:w-full ui:max-w-[calc(100%-2rem)] ui:translate-x-[-50%] ui:translate-y-[-50%] ui:gap-4 ui:rounded-lg ui:p-6 ui:shadow-lg ui:duration-200 ui:sm:max-w-lg',
+      // `has-[[data-slot=dialog-footer][data-sticky=true]]:pb-0` drops the
+      // dialog's own bottom padding when a sticky footer is rendered —
+      // the footer's own `py-4` provides the bottom spacing instead, and
+      // it pins flush with the dialog's bottom edge.
+      'ui:bg-background ui:border ui:data-[state=open]:animate-in ui:data-[state=closed]:animate-out ui:data-[state=closed]:fade-out-0 ui:data-[state=open]:fade-in-0 ui:data-[state=closed]:zoom-out-95 ui:data-[state=open]:zoom-in-95 ui:fixed ui:left-[50%] ui:top-[50%] ui:z-200 ui:grid ui:w-full ui:max-w-[calc(100%-2rem)] ui:translate-x-[-50%] ui:translate-y-[-50%] ui:gap-4 ui:rounded-lg ui:p-6 ui:[&:has([data-slot=dialog-footer][data-sticky=true])]:pb-0 ui:shadow-lg ui:duration-200 ui:sm:max-w-lg',
       className
     )}
     {...restProps}