F9: Small polish batch

- getYouTubeId also recognizes /embed/<id> and /shorts/<id> URLs (test
  renders all three variants as thumbnails on the exercise detail view)
- useListNavigation JSDoc: itemCount is a Ref<number>, not a number
- collectionRepository.getAll: N+1 per-collection count queries folded
  into one LEFT JOIN ... GROUP BY

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/composables/useListNavigation.js

@@ -3,9 +3,9 @@ import { ref, onMounted, onBeforeUnmount, nextTick } from 'vue'
 /**
  * Provides keyboard navigation for a list of items using arrow keys.
  *
- * @param {number} itemCount - The number of items in the list
+ * @param {import('vue').Ref<number>} itemCount - Ref holding the number of items in the list
  * @param {Function} onSelect - Callback when Enter is pressed on a focused item (receives index)
- * @returns {{ focusedIndex: Ref<number>, onKeydown: Function, focusItem: Function }}
+ * @returns {{ focusedIndex: import('vue').Ref<number>, onKeydown: Function, focusItem: Function }}
  */
 export function useListNavigation(itemCount, onSelect) {
   const focusedIndex = ref(-1)

src/db/repositories/collectionRepository.js

@@ -20,15 +20,13 @@ export const collectionRepository = {
   },
 
   async getAll() {
-    const collections = await db.selectAll('SELECT * FROM collection ORDER BY label')
-    for (const c of collections) {
-      const row = await db.selectOne(
-        'SELECT COUNT(*) AS sessionCount FROM collection_session WHERE collection_id = ?',
-        [c.id],
+    return db.selectAll(
+      `SELECT c.*, COUNT(cs.session_id) AS sessionCount
+       FROM collection c
+       LEFT JOIN collection_session cs ON cs.collection_id = c.id
+       GROUP BY c.id
+       ORDER BY c.label`,
     )
-      c.sessionCount = row ? row.sessionCount : 0
-    }
-    return collections
   },
 
   async getAllWithSessions() {

src/utils/youtube.js

@@ -5,6 +5,8 @@ export function getYouTubeId(url) {
       return u.pathname.slice(1)
     }
     if (u.hostname.includes('youtube.com')) {
+      const pathMatch = u.pathname.match(/^\/(?:embed|shorts)\/([^/?]+)/)
+      if (pathMatch) return pathMatch[1]
       return u.searchParams.get('v')
     }
   } catch {

tests/test_step3_exercises.py

@@ -9,6 +9,7 @@ Step 3 — Exercise Management Tests
 - test_delete_exercise: Delete an exercise with confirmation
 - test_delete_exercise_cancel: Cancelling delete does not remove exercise
 - test_delete_exercise_used_in_session: Delete confirm mentions usage; no session_item orphans
+- test_exercise_video_embed_and_shorts_urls: embed/shorts YouTube URLs render as thumbnails
 - test_search_exercises: Search filters exercises by title
 - test_search_no_results: Search with no matches shows empty message
 - test_search_clear_button: Clear button empties the search field and restores the full list
@@ -172,6 +173,46 @@ def test_create_exercise_full(page: Page, app_url: str):
     _clean_exercises(page)
 
 
+def test_exercise_video_embed_and_shorts_urls(page: Page, app_url: str):
+    """YouTube /embed/<id> and /shorts/<id> URLs are recognized like watch
+    URLs and render as thumbnails on the detail view."""
+    _go_to_exercises(page, app_url)
+    _clean_exercises(page)
+
+    exercise_id = page.evaluate(
+        """async () => {
+            const uuid = await window.__repos.settings.get('user_uuid');
+            return window.__repos.exercises.create({
+                title: 'Video URL Variants',
+                description: '',
+                asymmetric: false,
+                alternate: false,
+                image_urls: [],
+                video_urls: [
+                    'https://www.youtube.com/watch?v=dQw4w9WgXcQ',
+                    'https://www.youtube.com/embed/dQw4w9WgXcQ',
+                    'https://www.youtube.com/shorts/dQw4w9WgXcQ',
+                ],
+                default_reps: 10,
+                default_weight: 0,
+                created_by: uuid
+            });
+        }"""
+    )
+
+    page.goto(f"{app_url}/#/exercises/{exercise_id}")
+    page.wait_for_selector('[data-testid="exercise-detail-video-0"]', timeout=5000)
+
+    for i in range(3):
+        video = page.locator(f'[data-testid="exercise-detail-video-{i}"]')
+        expect(video).to_have_class("youtube-thumb")
+        expect(video.locator("img")).to_have_attribute(
+            "src", "https://img.youtube.com/vi/dQw4w9WgXcQ/mqdefault.jpg"
+        )
+
+    _clean_exercises(page)
+
+
 def test_exercise_appears_in_list(page: Page, app_url: str):
     """Created exercise appears in the list view with correct info."""
     _go_to_exercises(page, app_url)