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/logo-watermark.tsx

@@ -0,0 +1,39 @@
+import type { LogoPosition } from "@/lib/types";
+
+function logoPositionClass(pos?: LogoPosition) {
+  switch (pos) {
+    case "top_left":
+      return "top-0 left-0";
+    case "bottom_left":
+      return "bottom-0 left-0";
+    case "bottom_right":
+      return "bottom-0 right-0";
+    default:
+      return "top-0 right-0";
+  }
+}
+
+interface LogoWatermarkProps {
+  logo: string;
+  position?: LogoPosition;
+  opacity?: number;
+}
+
+export function LogoWatermark({ logo, position, opacity = 1 }: LogoWatermarkProps) {
+  return (
+    <div
+      className={`pointer-events-none absolute z-10 p-3 ${logoPositionClass(position)}`}
+      style={{ opacity }}
+    >
+      {logo.trimStart().startsWith("<") ? (
+        <div
+          dangerouslySetInnerHTML={{ __html: logo }}
+          className="h-12 w-auto"
+        />
+      ) : (
+        // eslint-disable-next-line @next/next/no-img-element
+        <img src={logo} alt="" className="h-12 w-auto object-contain" />
+      )}
+    </div>
+  );
+}