feat(channel): page details chaine multi-providers avec onglets et infinite scroll

- Strategy Pattern front: ChannelProviderInterface + 6 providers (yt/dm/tw/pt/od/ru) + factory (ids longs/courts)
- ChannelContentService: cache par onglet/tri/recherche (TTL 5min), pagination nextPage
- ChannelPage: header (banniere/avatar/subs/description ...plus), tabs dynamiques par capabilities, grilles videos/shorts 9:16/playlists/live, recherche debounced, tri recent/populaire, infinite scroll IntersectionObserver, skeletons/empty/error
- Backend: GET /api/channels/:provider/:id/content (videos/shorts/playlists/live) natif par provider

server/providers/dailymotion.mjs

@@ -20,7 +20,7 @@ const handler = {
           page: Math.max(1, Number(page || 1)).toString(),
           // Map our sort to Dailymotion API sort: relevance | visited (views) | recent (date)
           sort: (sort === 'date' ? 'recent' : (sort === 'views' ? 'visited' : 'relevance')),
-          fields: 'id,title,thumbnail_url,thumbnail_360_url,thumbnail_480_url,thumbnail_720_url,duration,views_total,owner.screenname,owner.avatar_80_url,created_time'
+          fields: 'id,title,thumbnail_url,thumbnail_360_url,thumbnail_480_url,thumbnail_720_url,duration,views_total,owner.id,owner.screenname,owner.avatar_80_url,created_time'
         })
       );
 
@@ -36,6 +36,7 @@ const handler = {
         url: `https://www.dailymotion.com/video/${item.id}`,
         thumbnail: item.thumbnail_720_url || item.thumbnail_480_url || item.thumbnail_360_url || item.thumbnail_url || '',
         uploaderName: item['owner.screenname'] || item['owner.username'] || '',
+        channelId: item['owner.id'] || item['owner.username'] || undefined,
         uploaderAvatar: item['owner.avatar_80_url'] || '',
         duration: Number(item.duration || 0),
         views: Number(item.views_total || 0),