refactor(frontend): extract logic to hooks, split inline components

Area 1 (tv/page.tsx 964→423 lines):
- hooks: use-fullscreen, use-idle, use-volume, use-quality, use-subtitles,
  use-channel-input, use-channel-passwords, use-tv-keyboard
- components: SubtitlePicker, VolumeControl, QualityPicker, TopControlBar,
  LogoWatermark, AutoplayPrompt, ChannelNumberOverlay, TvBaseLayer

Area 2 (edit-channel-sheet.tsx 1244→678 lines):
- hooks: use-channel-form (all form state + reset logic)
- lib/schemas.ts: extracted Zod schemas + extractErrors
- components: AlgorithmicFilterEditor, RecyclePolicyEditor, WebhookEditor,
  AccessSettingsEditor, LogoEditor

Area 3 (dashboard/page.tsx 406→261 lines):
- hooks: use-channel-order, use-import-channel, use-regenerate-all
- lib/channel-export.ts: pure export utility
- components: DashboardHeader

k-tv-frontend/hooks/use-channel-passwords.ts

@@ -0,0 +1,74 @@
+"use client";
+
+import { useState, useCallback } from "react";
+import { useQueryClient } from "@tanstack/react-query";
+
+export function useChannelPasswords(channelId?: string) {
+  const queryClient = useQueryClient();
+
+  const [channelPasswords, setChannelPasswords] = useState<Record<string, string>>(() => {
+    try {
+      return JSON.parse(localStorage.getItem("channel_passwords") ?? "{}");
+    } catch {
+      return {};
+    }
+  });
+  const [blockPasswords, setBlockPasswords] = useState<Record<string, string>>(() => {
+    try {
+      return JSON.parse(localStorage.getItem("block_passwords") ?? "{}");
+    } catch {
+      return {};
+    }
+  });
+  const [showChannelPasswordModal, setShowChannelPasswordModal] = useState(false);
+  const [showBlockPasswordModal, setShowBlockPasswordModal] = useState(false);
+
+  // channelPassword only depends on channelId — available immediately from localStorage
+  const channelPassword = channelId ? channelPasswords[channelId] : undefined;
+
+  // blockPassword is derived lazily by the caller (needs broadcast.slot.id)
+  const getBlockPassword = useCallback(
+    (slotId?: string) => (slotId ? blockPasswords[slotId] : undefined),
+    [blockPasswords],
+  );
+
+  const submitChannelPassword = useCallback(
+    (password: string) => {
+      if (!channelId) return;
+      const next = { ...channelPasswords, [channelId]: password };
+      setChannelPasswords(next);
+      try {
+        localStorage.setItem("channel_passwords", JSON.stringify(next));
+      } catch {}
+      setShowChannelPasswordModal(false);
+      queryClient.invalidateQueries({ queryKey: ["broadcast", channelId] });
+    },
+    [channelId, channelPasswords, queryClient],
+  );
+
+  const submitBlockPassword = useCallback(
+    (slotId: string, channelIdForQuery: string | undefined, password: string) => {
+      const next = { ...blockPasswords, [slotId]: password };
+      setBlockPasswords(next);
+      try {
+        localStorage.setItem("block_passwords", JSON.stringify(next));
+      } catch {}
+      setShowBlockPasswordModal(false);
+      queryClient.invalidateQueries({
+        queryKey: ["stream-url", channelIdForQuery, slotId],
+      });
+    },
+    [blockPasswords, queryClient],
+  );
+
+  return {
+    channelPassword,
+    getBlockPassword,
+    showChannelPasswordModal,
+    setShowChannelPasswordModal,
+    showBlockPasswordModal,
+    setShowBlockPasswordModal,
+    submitChannelPassword,
+    submitBlockPassword,
+  };
+}