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-tv-keyboard.ts

@@ -0,0 +1,78 @@
+"use client";
+
+import { useEffect, useRef } from "react";
+import type { SubtitleTrack } from "@/app/(main)/tv/components/video-player";
+
+interface UseTvKeyboardOptions {
+  nextChannel: () => void;
+  prevChannel: () => void;
+  toggleSchedule: () => void;
+  toggleFullscreen: () => void;
+  toggleMute: () => void;
+  setShowStats: React.Dispatch<React.SetStateAction<boolean>>;
+  subtitleTracks: SubtitleTrack[];
+  setActiveSubtitleTrack: React.Dispatch<React.SetStateAction<number>>;
+  handleDigit: (digit: string) => void;
+}
+
+export function useTvKeyboard(opts: UseTvKeyboardOptions) {
+  const optsRef = useRef(opts);
+  useEffect(() => {
+    optsRef.current = opts;
+  });
+
+  useEffect(() => {
+    const handleKey = (e: KeyboardEvent) => {
+      if (
+        e.target instanceof HTMLInputElement ||
+        e.target instanceof HTMLTextAreaElement
+      )
+        return;
+
+      const o = optsRef.current;
+      switch (e.key) {
+        case "ArrowUp":
+        case "PageUp":
+          e.preventDefault();
+          o.nextChannel();
+          break;
+        case "ArrowDown":
+        case "PageDown":
+          e.preventDefault();
+          o.prevChannel();
+          break;
+        case "s":
+        case "S":
+          o.setShowStats((v) => !v);
+          break;
+        case "g":
+        case "G":
+          o.toggleSchedule();
+          break;
+        case "f":
+        case "F":
+          o.toggleFullscreen();
+          break;
+        case "m":
+        case "M":
+          o.toggleMute();
+          break;
+        case "c":
+        case "C":
+          if (o.subtitleTracks.length > 0) {
+            o.setActiveSubtitleTrack((prev) =>
+              prev === -1 ? o.subtitleTracks[0].id : -1,
+            );
+          }
+          break;
+        default:
+          if (e.key >= "0" && e.key <= "9") {
+            o.handleDigit(e.key);
+          }
+      }
+    };
+
+    window.addEventListener("keydown", handleKey);
+    return () => window.removeEventListener("keydown", handleKey);
+  }, []);
+}