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-channel-input.ts

@@ -0,0 +1,39 @@
+"use client";
+
+import { useState, useEffect, useCallback, useRef } from "react";
+
+export function useChannelInput(
+  channelCount: number,
+  switchChannel: (idx: number) => void,
+  resetIdle: () => void,
+) {
+  const [channelInput, setChannelInput] = useState("");
+  const channelInputTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  const handleDigit = useCallback(
+    (digit: string) => {
+      setChannelInput((prev) => {
+        const next = prev + digit;
+        if (channelInputTimer.current) clearTimeout(channelInputTimer.current);
+        channelInputTimer.current = setTimeout(() => {
+          const num = parseInt(next, 10);
+          if (num >= 1 && num <= Math.max(channelCount, 1)) {
+            switchChannel(num - 1);
+            resetIdle();
+          }
+          setChannelInput("");
+        }, 1500);
+        return next;
+      });
+    },
+    [channelCount, switchChannel, resetIdle],
+  );
+
+  useEffect(() => {
+    return () => {
+      if (channelInputTimer.current) clearTimeout(channelInputTimer.current);
+    };
+  }, []);
+
+  return { channelInput, handleDigit };
+}