fix(dashboard): course landing page editor section and currency bugs (#768)

* fix(dashboard): course landing page editor section and currency bugs

- Raise currency select z-index so the dropdown is clickable in the
  full-screen editor shell
- Show dashed top/bottom borders and section title on hover and when
  active in EditableLandingSection
- Map hero/header section keys in the course editor preview context

Co-authored-by: Rotimi Best <[email protected]>

* fix(ui): format course landing page pricing with Intl currency

Use getCourseCurrencyFormatter (matching dashboard getCurrencyFormatter)
so NGN and USD prices render as proper locale currency strings instead of
raw numbers with a currency code suffix.

Co-authored-by: Rotimi Best <[email protected]>

* fix(ui): prefix group class for landing section hover badge

Co-authored-by: Rotimi Best <[email protected]>

* fix(ui): remove unused formatCourseCurrency helper

Co-authored-by: Rotimi Best <[email protected]>

* refactor: move currency formatter to @cio/utils

Shared course price formatting belongs in @cio/utils, not the UI
package. Dashboard re-exports the helper to keep existing imports.

Co-authored-by: Rotimi Best <[email protected]>

---------

apps/dashboard/src/lib/features/ui/course-landing-page/components/editor/pricing-form.svelte

@@ -48,7 +48,7 @@
       <Select.Trigger class="w-full">
         <p>{course.currency === 'NGN' ? 'NGN' : 'USD'}</p>
       </Select.Trigger>
-      <Select.Content>
+      <Select.Content class="z-menu-elevated">
         <Select.Item value="NGN">NGN</Select.Item>
         <Select.Item value="USD">USD</Select.Item>
       </Select.Content>