feat: add StreamEmbed widget, move course progress to footer corner

- Add StreamEmbed component supporting Twitch and YouTube embeds
  with live badge, platform icon, aspect-ratio 16:9, external link
- Replace AudioPlayer on AdminHome with StreamEmbed (configure
  channel name in streamConfig ref)
- Move course progress % to bottom-right footer corner alongside
  price/cert badge; remove separate progress row above footer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/CourseCard.vue

@@ -84,7 +84,7 @@
 			<div class="flex-1" />
 
 			<!-- Stats row -->
-			<div class="flex items-center gap-3 text-xs text-ink-gray-5 mb-2 flex-wrap">
+			<div class="flex items-center gap-3 text-xs text-ink-gray-5 mb-3 flex-wrap">
 				<span v-if="course.lessons" class="flex items-center gap-1">
 					<BookOpen class="h-3.5 w-3.5" />
 					{{ course.lessons }} {{ __('lessons') }}
@@ -99,11 +99,6 @@
 				</span>
 			</div>
 
-			<!-- Progress text -->
-			<div v-if="user && course.membership" class="text-xs text-ink-gray-5 mb-2">
-				{{ Math.ceil(course.membership.progress) }}% {{ __('completed') }}
-			</div>
-
 			<!-- Footer -->
 			<div class="flex items-center justify-between pt-3 border-t border-outline-gray-1">
 				<!-- Instructors -->
@@ -123,9 +118,15 @@
 					/>
 				</div>
 
-				<!-- Right side: price + cert -->
+				<!-- Right side: progress % / price / cert -->
 				<div class="flex items-center gap-2">
-					<span v-if="course.paid_course" class="text-sm font-semibold text-ink-gray-9">
+					<span
+						v-if="user && course.membership"
+						class="text-xs font-medium text-ink-green-3"
+					>
+						{{ Math.ceil(course.membership.progress) }}%
+					</span>
+					<span v-else-if="course.paid_course" class="text-sm font-semibold text-ink-gray-9">
 						{{ course.price }}
 					</span>
 					<Tooltip