feat(channels): add a Hidden tab; move hidden channels out of Subscriptions (R13 S2)

Hidden subscriptions get their own tab (mirroring Blocked): a flat list with an
Unhide action, instead of dimmed rows scattered through the Subscriptions table.
- ChannelsView += "hidden"; the subscribed table now EXCLUDES hidden channels,
  so hiding a channel (the eye button) moves it to the Hidden tab and unhiding
  (Eye) returns it — both via the existing patch mutation.
- The "Hidden" top-level status chip is dropped (ChannelStatusFilter loses
  "hidden"); the status row is now purely sync-status (all/needs_full/fully_synced).
- Bilingual i18n (en/hu): channels.tabs.hidden + a channels.hidden block; the now
  unused channels.filters.hidden removed.

Hidden = out of the personal (Mine) feed only, still in the shared Library — a
softer exclusion than Blocked (hidden everywhere). Gate green: tsc/eslint-0/
prettier/vitest 106. Self-E2E'd: hide → appears in Hidden tab → unhide → back,
all /api 200.

frontend/src/components/Channels.tsx

@@ -2,7 +2,7 @@ import { useEffect, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { qk } from "../lib/queryKeys";
-import { Ban, History, LayoutGrid, Pencil, RefreshCw, Table, X } from "lucide-react";
+import { Ban, Eye, EyeOff, History, LayoutGrid, Pencil, RefreshCw, Table, X } from "lucide-react";
 import { api, type ManagedChannel } from "../lib/api";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import { accountKey, LS } from "../lib/storage";
@@ -31,15 +31,14 @@ import { useFeedFilters, useFeedFiltersActions } from "./FeedFiltersProvider";
 import { useWizard } from "./WizardProvider";
 import { useMe } from "../lib/useMe";
 
-export type ChannelsView = "subscribed" | "discovery" | "blocked";
+export type ChannelsView = "subscribed" | "discovery" | "hidden" | "blocked";
 
-export type ChannelStatusFilter = "all" | "needs_full" | "fully_synced" | "hidden";
+export type ChannelStatusFilter = "all" | "needs_full" | "fully_synced";
 
 const STATUS_FILTERS: { id: ChannelStatusFilter; labelKey: string }[] = [
   { id: "all", labelKey: "channels.filters.all" },
   { id: "needs_full", labelKey: "channels.filters.needsFull" },
   { id: "fully_synced", labelKey: "channels.filters.fullySynced" },
-  { id: "hidden", labelKey: "channels.filters.hidden" },
 ];
 
 const LAYOUT_ICON: Record<ChannelLayout, typeof Table> = {
@@ -225,16 +224,18 @@ export default function Channels() {
 
   // The Sync-status filter stays a top-level chip set (not a column filter) because the
   // header's "go to full history" deep-link drives it; search/tag filtering + sort + pagination
-  // run over whatever the status chip leaves.
-  const channels = (channelsQuery.data ?? []).filter((c) =>
-    statusFilter === "needs_full"
-      ? !c.backfill_done
-      : statusFilter === "fully_synced"
-        ? c.backfill_done
-        : statusFilter === "hidden"
-          ? c.hidden
+  // run over whatever the status chip leaves. Hidden channels have their own tab, so they're
+  // excluded from the subscribed table (no more dimmed rows) rather than shown via a status chip.
+  const hiddenChannels = (channelsQuery.data ?? []).filter((c) => c.hidden);
+  const channels = (channelsQuery.data ?? [])
+    .filter((c) => !c.hidden)
+    .filter((c) =>
+      statusFilter === "needs_full"
+        ? !c.backfill_done
+        : statusFilter === "fully_synced"
+          ? c.backfill_done
           : true,
-  );
+    );
   const q = search.trim().toLowerCase();
   const visibleChannels = channels.filter((c) => {
     if (q && !`${c.title ?? ""} ${c.handle ?? ""}`.toLowerCase().includes(q)) return false;
@@ -426,7 +427,7 @@ export default function Channels() {
   const tabs = (
     <div className="px-4 pt-4 max-w-384 mx-auto flex items-center justify-between gap-4 flex-wrap">
       <div className="flex flex-wrap items-center gap-1.5">
-        {(["subscribed", "discovery", "blocked"] as ChannelsView[]).map((v) => (
+        {(["subscribed", "discovery", "hidden", "blocked"] as ChannelsView[]).map((v) => (
           <button
             key={v}
             onClick={() => setView(v)}
@@ -553,6 +554,42 @@ export default function Channels() {
             </>
           )}
         </div>
+      ) : view === "hidden" ? (
+        /* Hidden channels — kept out of the Mine feed but still in the shared Library; managed here
+           instead of dimmed in the subscribed table. Mirrors the Blocked tab (flat list + one action). */
+        <div className="px-4 pb-4 pt-3 max-w-384 mx-auto">
+          {hiddenChannels.length === 0 ? (
+            <p className="text-sm text-muted py-8">{t("channels.hidden.empty")}</p>
+          ) : (
+            <>
+              <div className="flex items-center gap-2 mb-3">
+                <EyeOff className="w-4 h-4 text-muted" />
+                <span className="text-xs uppercase tracking-wide text-muted">
+                  {t("channels.hidden.title")}
+                </span>
+              </div>
+              <div className="flex flex-wrap gap-1.5">
+                {hiddenChannels.map((c) => (
+                  <span
+                    key={c.id}
+                    className="inline-flex items-center gap-1.5 text-xs pl-2.5 pr-1 py-1 rounded-full bg-card border border-border"
+                  >
+                    {c.title ?? c.id}
+                    <button
+                      onClick={() => patch.mutate({ id: c.id, body: { hidden: false } })}
+                      title={t("channels.hidden.unhide")}
+                      aria-label={t("channels.hidden.unhide")}
+                      className="rounded-full p-0.5 text-muted hover:text-accent transition"
+                    >
+                      <Eye className="w-3 h-3" />
+                    </button>
+                  </span>
+                ))}
+              </div>
+              <p className="text-2xs text-muted mt-2">{t("channels.hidden.hint")}</p>
+            </>
+          )}
+        </div>
       ) : (
         /* No top padding: the sticky header sits flush at the scroller top so it doesn't shift when
          `position: sticky` engages on the first scroll (the band's controls row above gives the