feat(dashboard): improve student course sidebar navigation (#814)

* docs(prototypes): add course sidebar navigation HTML prototypes

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* docs(prototypes): add downloadable zip for course sidebar mockups

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* feat(dashboard): improve student course sidebar navigation

Collapse all sections except the active one for students, show section
completion as counts (e.g. 3/4), and replace the footer progress card with
prev/next controls plus a thin progress bar.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): address PR review and remove sidebar prototypes

Remove HTML prototype files from the PR. Match content IDs as exact path
segments for active-item resolution, and use content-neutral prev/next labels.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): keep ClassroomIO brand untranslated in powered-by footer

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): restore progress summary in course sidebar footer

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): move progress bar below summary in sidebar footer

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* feat(course): add mobile student bottom nav with outline sheet

Implement prototype 3 mobile navigation for course learners: a fixed
bottom bar with progress ring, prev/next controls, and a sheet showing
the progress card plus collapsible course outline with scroll-to-active.

Extends public-course UI primitives (ring bottom nav, collapsible
sidebar sections, mobile sheet progress slot) and wires them into the
authenticated course layout for isCourseLearnerView on lesson/exercise
routes. Hides duplicate header prev/next and progress popover on mobile.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(course): address review feedback and exclude prototypes

- Add .coderabbit.yaml and .greptile/config.json to skip prototypes/**
- Document prototypes/ as out-of-scope in AGENTS.md and Greptile rules
- Render locked mobile outline rows without href navigation targets
- Replace nested IconButton in collapsible section trigger with chevron icon
- Reset public-course sidebar section collapse on every mobile sheet reopen

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

---------

apps/dashboard/src/lib/features/course/pages/exercise.svelte

@@ -30,7 +30,10 @@
   import { ZExerciseUpdate } from '@cio/utils/validation/exercise';
   import { mapZodErrorsToTranslations } from '$lib/utils/validation';
   import { transformQuestionsToApiFormat } from '$features/course/components/exercise/functions';
-  import { isOrgStudent, isStudentExperience } from '$lib/utils/store/app';
+  import { isOrgStudent, isCourseLearnerView, isStudentExperience } from '$lib/utils/store/app';
+  import { isMobileStore } from '@cio/ui/hooks/is-mobile.svelte';
+  import { getCourseProgress } from '$features/course/utils/content';
+  import { isCourseMobileBottomNavVisible } from '$features/course/utils/mobile-bottom-nav';
   import { t } from '$lib/utils/functions/translations';
   import { snackbar } from '$features/ui/snackbar/store';
   import { exerciseApi } from '$features/course/api';
@@ -89,6 +92,15 @@
     mySubmissions = []
   }: Props = $props();
 
+  const showMobileBottomNav = $derived(
+    isCourseMobileBottomNavVisible({
+      isCourseLearnerView: $isCourseLearnerView,
+      isMobile: isMobileStore.current,
+      isLessonOrExercisePage: Boolean(exerciseId),
+      courseProgress: getCourseProgress(courseApi.course)
+    })
+  );
+
   type ExerciseTab = 'questions' | 'settings' | 'submissions';
 
   function normalizeExerciseTab(tabParam: string | null): ExerciseTab {
@@ -626,7 +638,7 @@
   </Page.HeaderContent>
   <Page.Action>
     <div class="flex items-center gap-2">
-      {#if $isStudentExperience && courseApi.course?.id && exerciseId}
+      {#if $isCourseLearnerView && courseApi.course?.id && exerciseId && !showMobileBottomNav}
         <ContentNavigationActions courseId={courseApi.course.id} {exerciseId} />
       {/if}