feat(notifications): link the subscribe activity to the channel

The "Subscribed on YouTube" inbox entry now names the channel and offers
two convenience links that survive a reload (driven by the typed payload,
not the live callback): "Channel manager" (jumps to the manager focused on
that channel) and "Open on YouTube". Wires the panel to the app's
focus-channel navigation; trilingual strings.

frontend/src/App.tsx

@@ -451,7 +451,7 @@ export default function App() {
           ) : page === "playlists" ? (
             <Playlists canWrite={meQuery.data!.can_write} />
           ) : page === "notifications" ? (
-            <NotificationsPanel filters={filters} setFilters={setFilters} setPage={setPage} />
+            <NotificationsPanel filters={filters} setFilters={setFilters} setPage={setPage} onFocusChannel={focusChannel} />
           ) : page === "settings" ? (
             <SettingsPanel
               me={meQuery.data!}

frontend/src/components/NotificationsPanel.tsx

@@ -1,7 +1,7 @@
 import { useEffect, useSyncExternalStore } from "react";
 import { useTranslation } from "react-i18next";
 import { useMutation, useQueryClient } from "@tanstack/react-query";
-import { Bell, Check, CheckCheck, Eye, RotateCcw, Search, Trash2, X } from "lucide-react";
+import { Bell, Check, CheckCheck, ExternalLink, Eye, RotateCcw, Search, Trash2, Tv, X } from "lucide-react";
 import { api, type AppNotification, type FeedFilters } from "../lib/api";
 import { useLiveQuery } from "../lib/useLiveQuery";
 import {
@@ -14,6 +14,7 @@ import {
   resolveVideo,
   subscribe,
   type Notification as ClientNotif,
+  type ChannelSubscribedMeta,
   type VideoHiddenMeta,
   type VideoWatchedMeta,
 } from "../lib/notifications";
@@ -46,10 +47,12 @@ export default function NotificationsPanel({
   filters,
   setFilters,
   setPage,
+  onFocusChannel,
 }: {
   filters: FeedFilters;
   setFilters: (f: FeedFilters) => void;
   setPage: (p: Page) => void;
+  onFocusChannel: (name: string) => void;
 }) {
   const { t } = useTranslation();
   const qc = useQueryClient();
@@ -183,6 +186,7 @@ export default function NotificationsPanel({
                     t={t}
                     onFind={locateHidden}
                     onRevert={revertState}
+                    onFocusChannel={onFocusChannel}
                     onRemove={() => removeClient(n.id)}
                   />
                 ))}
@@ -287,18 +291,22 @@ function ClientActivityRow({
   t,
   onFind,
   onRevert,
+  onFocusChannel,
   onRemove,
 }: {
   n: ClientNotif;
   t: (k: string, o?: any) => string;
   onFind: (meta: VideoHiddenMeta) => void;
   onRevert: (meta: VideoHiddenMeta | VideoWatchedMeta) => void;
+  onFocusChannel: (name: string) => void;
   onRemove: () => void;
 }) {
   const { icon: Icon, color } = LEVEL_STYLE[n.level];
   const needsAction = n.requiresInteraction && !n.dismissed;
   const hidden = n.meta?.kind === "video-hidden" ? n.meta : null;
   const watched = n.meta?.kind === "video-watched" ? n.meta : null;
+  const subscribed: ChannelSubscribedMeta | null =
+    n.meta?.kind === "channel-subscribed" ? n.meta : null;
   return (
     <div
       className={`glass rounded-xl p-3.5 flex items-start gap-3 ${needsAction ? "ring-1 ring-accent/30" : ""}`}
@@ -342,6 +350,25 @@ function ClientActivityRow({
               {t("notifications.unwatch")}
             </button>
           </div>
+        ) : subscribed ? (
+          <div className="flex items-center gap-3 mt-1">
+            <button
+              onClick={() => onFocusChannel(subscribed.channelName)}
+              className="flex items-center gap-1 text-accent text-sm font-semibold hover:underline"
+            >
+              <Tv className="w-3.5 h-3.5" />
+              {t("notifications.openInManager")}
+            </button>
+            <a
+              href={`https://www.youtube.com/channel/${subscribed.channelId}`}
+              target="_blank"
+              rel="noopener noreferrer"
+              className="flex items-center gap-1 text-accent text-sm font-semibold hover:underline"
+            >
+              <ExternalLink className="w-3.5 h-3.5" />
+              {t("notifications.openOnYouTube")}
+            </a>
+          </div>
         ) : (
 
           n.action &&

frontend/src/i18n/locales/de/notifications.json

@@ -8,6 +8,8 @@
   "findInFeed": "Im Feed finden",
   "unhide": "Einblenden",
   "unwatch": "Nicht angesehen",
+  "openInManager": "Kanalverwaltung",
+  "openOnYouTube": "Auf YouTube öffnen",
   "unhidden": "Eingeblendet „{{title}}”",
   "unwatched": "Als nicht angesehen markiert „{{title}}”",
   "time": {

frontend/src/i18n/locales/en/notifications.json

@@ -8,6 +8,8 @@
   "findInFeed": "Find in feed",
   "unhide": "Unhide",
   "unwatch": "Unwatch",
+  "openInManager": "Channel manager",
+  "openOnYouTube": "Open on YouTube",
   "unhidden": "Unhidden “{{title}}”",
   "unwatched": "Unwatched “{{title}}”",
   "time": {

frontend/src/i18n/locales/hu/notifications.json

@@ -8,6 +8,8 @@
   "findInFeed": "Keresés a hírfolyamban",
   "unhide": "Megjelenítés",
   "unwatch": "Megtekintés visszavonása",
+  "openInManager": "Csatornakezelő",
+  "openOnYouTube": "Megnyitás a YouTube-on",
   "unhidden": "Megjelenítve: „{{title}}”",
   "unwatched": "Megtekintés visszavonva: „{{title}}”",
   "time": {