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

src/app/search/adapters/tw.ts

@@ -13,7 +13,13 @@ export class TwAdapter implements ProviderAdapter<VideoItem> {
     if (params.sort) httpParams = httpParams.set('sort', params.sort);
     const res = await firstValueFrom(this.http.get<any>(`/api/search`, { params: httpParams }));
     const items: VideoItem[] = (res?.groups?.tw || []).map((it: any) => {
-      const isChannel = String(it?.type || '').toLowerCase() === 'channel';
+      // /api/search (tw) ne retourne que des chaînes : le player exige le login
+      // (?channel=<login>), jamais l'id numérique. Sans `channel`, /watch tente
+      // ?video=<id> et Twitch répond par une erreur.
+      const login: string | undefined =
+        it.channelExternalId || it.channelHandle || undefined;
+      const kind = String(it?.type || '').toLowerCase();
+      const isChannel = kind === 'channel' || kind === 'live' || Boolean(login);
       return {
         id: it.id,
         provider: 'twitch',
@@ -23,7 +29,10 @@ export class TwAdapter implements ProviderAdapter<VideoItem> {
         thumbnailUrl: it.thumbnail,
         viewCount: typeof it.views === 'number' ? it.views : undefined,
         publishedAt: it.publishedAt,
-        channel: isChannel ? it.id : undefined,
+        channelExternalId: login,
+        channelAvatarUrl: it.uploaderAvatar || undefined,
+        // Login pour l'embed ?channel=... (video-card -> watchQueryParams).
+        channel: isChannel ? login : undefined,
       } as VideoItem;
     });
     return { items, total: Array.isArray(res?.groups?.tw) ? res.groups.tw.length : 0 };