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/autoplay-prompt.tsx

@@ -0,0 +1,11 @@
+export function AutoplayPrompt() {
+  return (
+    <div className="pointer-events-none absolute inset-0 z-20 flex items-center justify-center">
+      <div className="rounded-xl bg-black/70 px-8 py-5 text-center backdrop-blur-sm">
+        <p className="text-sm font-medium text-zinc-200">
+          Click or move the mouse to play
+        </p>
+      </div>
+    </div>
+  );
+}