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/app/(main)/tv/components/tv-base-layer.tsx

@@ -0,0 +1,140 @@
+import { RefObject } from "react";
+import type { CurrentBroadcastResponse } from "@/lib/types";
+import { VideoPlayer } from "./video-player";
+import { NoSignal } from "./no-signal";
+import { calcOffsetSecs } from "@/hooks/use-tv";
+import type { SubtitleTrack } from "./video-player";
+
+interface TvBaseLayerProps {
+  isLoadingChannels: boolean;
+  hasChannels: boolean;
+  broadcastError: unknown;
+  isLoadingBroadcast: boolean;
+  hasBroadcast: boolean;
+  streamUrlError: unknown;
+  streamError: boolean;
+  videoEnded: boolean;
+  streamUrl?: string | null;
+  broadcast?: CurrentBroadcastResponse | null;
+  activeSubtitleTrack: number;
+  isMuted: boolean;
+  showStats: boolean;
+  videoRef: RefObject<HTMLVideoElement | null>;
+  onSubtitleTracksChange: (tracks: SubtitleTrack[]) => void;
+  onStreamError: () => void;
+  onEnded: () => void;
+  onNeedsInteraction: () => void;
+  onRetry: () => void;
+}
+
+export function TvBaseLayer({
+  isLoadingChannels,
+  hasChannels,
+  broadcastError,
+  isLoadingBroadcast,
+  hasBroadcast,
+  streamUrlError,
+  streamError,
+  videoEnded,
+  streamUrl,
+  broadcast,
+  activeSubtitleTrack,
+  isMuted,
+  showStats,
+  videoRef,
+  onSubtitleTracksChange,
+  onStreamError,
+  onEnded,
+  onNeedsInteraction,
+  onRetry,
+}: TvBaseLayerProps) {
+  if (isLoadingChannels) {
+    return <NoSignal variant="loading" message="Tuning in…" />;
+  }
+  if (!hasChannels) {
+    return (
+      <NoSignal
+        variant="no-signal"
+        message="No channels configured. Visit the Dashboard to create one."
+      />
+    );
+  }
+
+  const broadcastErrMsg = (broadcastError as Error)?.message;
+  if (broadcastErrMsg === "auth_required") {
+    return (
+      <NoSignal variant="locked" message="Sign in to watch this channel." />
+    );
+  }
+  if (
+    broadcastErrMsg &&
+    broadcastError &&
+    (broadcastError as { status?: number }).status === 403
+  ) {
+    return (
+      <NoSignal variant="locked" message="This channel is owner-only." />
+    );
+  }
+
+  if (isLoadingBroadcast) {
+    return <NoSignal variant="loading" message="Tuning in…" />;
+  }
+  if (!hasBroadcast) {
+    return (
+      <NoSignal
+        variant="no-signal"
+        message="Nothing is scheduled right now. Check back later."
+      />
+    );
+  }
+
+  const streamErrMsg = (streamUrlError as Error)?.message;
+  if (streamErrMsg === "auth_required") {
+    return (
+      <NoSignal variant="locked" message="Sign in to watch this block." />
+    );
+  }
+  if (
+    streamUrlError &&
+    (streamUrlError as { status?: number }).status === 403
+  ) {
+    return <NoSignal variant="locked" message="This block is owner-only." />;
+  }
+
+  if (streamError) {
+    return (
+      <NoSignal variant="error" message="Stream failed to load.">
+        <button
+          onClick={onRetry}
+          className="mt-2 rounded-md border border-zinc-700 bg-zinc-800/80 px-4 py-2 text-xs text-zinc-300 transition-colors hover:bg-zinc-700 hover:text-zinc-100"
+        >
+          Retry
+        </button>
+      </NoSignal>
+    );
+  }
+  if (videoEnded) {
+    return <NoSignal variant="loading" message="Up next, stay tuned…" />;
+  }
+  if (streamUrl) {
+    return (
+      <VideoPlayer
+        ref={videoRef}
+        src={streamUrl}
+        className="absolute inset-0 h-full w-full"
+        initialOffset={
+          broadcast ? calcOffsetSecs(broadcast.slot.start_at) : 0
+        }
+        subtitleTrack={activeSubtitleTrack}
+        muted={isMuted}
+        showStats={showStats}
+        broadcast={broadcast ?? undefined}
+        onSubtitleTracksChange={onSubtitleTracksChange}
+        onStreamError={onStreamError}
+        onEnded={onEnded}
+        onNeedsInteraction={onNeedsInteraction}
+      />
+    );
+  }
+  return <NoSignal variant="loading" message="Loading stream…" />;
+}