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)/dashboard/components/dashboard-header.tsx

@@ -0,0 +1,85 @@
+import { Plus, Upload, RefreshCw, Antenna, Settings2 } from "lucide-react";
+import { Button } from "@/components/ui/button";
+import type { ProviderCapabilities } from "@/lib/types";
+
+interface DashboardHeaderProps {
+  hasChannels: boolean;
+  canTranscode: boolean;
+  canRescan: boolean;
+  isRegeneratingAll: boolean;
+  isRescanPending: boolean;
+  capabilities: ProviderCapabilities | undefined;
+  onTranscodeOpen: () => void;
+  onRescan: () => void;
+  onRegenerateAll: () => void;
+  onIptvOpen: () => void;
+  onImportOpen: () => void;
+  onCreateOpen: () => void;
+}
+
+export function DashboardHeader({
+  hasChannels,
+  canTranscode,
+  canRescan,
+  isRegeneratingAll,
+  isRescanPending,
+  onTranscodeOpen,
+  onRescan,
+  onRegenerateAll,
+  onIptvOpen,
+  onImportOpen,
+  onCreateOpen,
+}: DashboardHeaderProps) {
+  return (
+    <div className="flex items-center justify-between">
+      <div>
+        <h1 className="text-xl font-semibold text-zinc-100">My Channels</h1>
+        <p className="mt-0.5 text-sm text-zinc-500">Build your broadcast lineup</p>
+      </div>
+      <div className="flex gap-2">
+        {canTranscode && (
+          <Button onClick={onTranscodeOpen} title="Transcode settings">
+            <Settings2 className="size-4" />
+            Transcode
+          </Button>
+        )}
+        {canRescan && (
+          <Button
+            onClick={onRescan}
+            disabled={isRescanPending}
+            title="Rescan local files directory"
+          >
+            <RefreshCw
+              className={`size-4 ${isRescanPending ? "animate-spin" : ""}`}
+            />
+            Rescan library
+          </Button>
+        )}
+        {hasChannels && (
+          <Button
+            onClick={onRegenerateAll}
+            disabled={isRegeneratingAll}
+            title="Regenerate schedules for all channels"
+          >
+            <RefreshCw
+              className={`size-4 ${isRegeneratingAll ? "animate-spin" : ""}`}
+            />
+            Regenerate all
+          </Button>
+        )}
+        <Button onClick={onIptvOpen}>
+          <Antenna className="size-4" />
+          IPTV
+        </Button>
+        <Button onClick={onImportOpen}>
+          <Upload className="size-4" />
+          Import
+        </Button>
+        <Button onClick={onCreateOpen}>
+          <Plus className="size-4" />
+          New channel
+        </Button>
+      </div>
+    </div>
+  );
+}