feat(channel): identite chaine partagee cliquable partout + logos fiabilises

- Nouveau app-channel-identity (avatar+nom -> /channel, fallback resolve /api/channels, initiales sinon)
- ProviderBadge: accepte les ids courts yt/dm/tw/pt/od/ru
- Search adapters yt/dm/pt/od: conservent channelExternalId/channelAvatarUrl (pt derive instance|channel)
- video-card/themes/watch/related/suggestions/subscriptions/channel-header uniformises sur l'identite partagee

src/components/library/subscriptions/subscriptions.component.html

@@ -63,16 +63,19 @@
           >
             <ng-container *ngIf="item.channel as channel; else subscriptionFallback">
               <div class="flex items-center gap-4">
-                <img
-                  [src]="channel.avatarUrl || 'https://placehold.co/80x80/png'"
-                  [alt]="channel.title || channel.handle || 'Avatar'"
-                  class="h-16 w-16 rounded-full border border-slate-800 object-cover"
-                />
+                <a [routerLink]="['/channel', channel.provider, channel.externalId]" title="Ouvrir la page de la chaîne">
+                  <img
+                    [src]="channel.avatarUrl || 'https://placehold.co/80x80/png'"
+                    [alt]="channel.title || channel.handle || 'Avatar'"
+                    class="h-16 w-16 rounded-full border border-slate-800 object-cover hover:ring-2 hover:ring-red-500/60"
+                  />
+                </a>
                 <div class="space-y-1">
                   <div class="flex flex-wrap items-center gap-2">
-                    <h3 class="text-lg font-semibold text-slate-100">
+                    <a [routerLink]="['/channel', channel.provider, channel.externalId]"
+                       class="text-lg font-semibold text-slate-100 hover:text-red-300">
                       {{ channel.title || channel.handle || 'Chaîne inconnue' }}
-                    </h3>
+                    </a>
                     <app-provider-badge [provider]="channel.provider"></app-provider-badge>
                     <span *ngIf="channel.verified" class="text-xs text-emerald-300">✓ Vérifiée</span>
                   </div>