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/subtitle-picker.tsx

@@ -0,0 +1,53 @@
+import type { SubtitleTrack } from "./video-player";
+
+interface SubtitlePickerProps {
+  tracks: SubtitleTrack[];
+  activeTrack: number;
+  show: boolean;
+  onToggle: () => void;
+  onChangeTrack: (id: number) => void;
+}
+
+export function SubtitlePicker({
+  tracks,
+  activeTrack,
+  show,
+  onToggle,
+  onChangeTrack,
+}: SubtitlePickerProps) {
+  if (tracks.length === 0) return null;
+  return (
+    <div className="pointer-events-auto relative">
+      <button
+        className="rounded-md bg-black/50 px-3 py-1.5 text-xs backdrop-blur transition-colors hover:bg-black/70 hover:text-white"
+        style={{
+          color: activeTrack !== -1 ? "white" : undefined,
+          borderBottom:
+            activeTrack !== -1 ? "2px solid white" : "2px solid transparent",
+        }}
+        onClick={onToggle}
+      >
+        CC
+      </button>
+      {show && (
+        <div className="absolute right-0 top-9 z-30 min-w-[10rem] overflow-hidden rounded-md border border-zinc-700 bg-zinc-900/95 py-1 shadow-xl backdrop-blur">
+          <button
+            className={`w-full px-3 py-1.5 text-left text-xs transition-colors hover:bg-zinc-700 ${activeTrack === -1 ? "text-white" : "text-zinc-400"}`}
+            onClick={() => onChangeTrack(-1)}
+          >
+            Off
+          </button>
+          {tracks.map((track) => (
+            <button
+              key={track.id}
+              className={`w-full px-3 py-1.5 text-left text-xs transition-colors hover:bg-zinc-700 ${activeTrack === track.id ? "text-white" : "text-zinc-400"}`}
+              onClick={() => onChangeTrack(track.id)}
+            >
+              {track.name || track.lang || `Track ${track.id + 1}`}
+            </button>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}