feat(ThemeSwitch): create ThemeSwitch component that uses ThemeMager toggle to switch theme

src/features/ChangeAppTheme/ui/ThemeSwitch/ThemeSwitch.svelte

@@ -0,0 +1,26 @@
+<!--
+    Component: ThemeSwitch
+    Toggles the theme between light and dark mode.
+-->
+<script lang="ts">
+import type { ResponsiveManager } from '$shared/lib';
+import { IconButton } from '$shared/ui';
+import MoonIcon from '@lucide/svelte/icons/moon';
+import SunIcon from '@lucide/svelte/icons/sun';
+import { getContext } from 'svelte';
+import { themeManager } from '../../model';
+
+const responsive = getContext<ResponsiveManager>('responsive');
+
+const theme = $derived(themeManager.value);
+</script>
+
+<IconButton onclick={() => themeManager.toggle()} size={responsive.isMobile ? 'sm' : 'md'} title="Toggle theme">
+    {#snippet icon()}
+        {#if theme === 'light'}
+            <MoonIcon />
+        {:else}
+            <SunIcon />
+        {/if}
+    {/snippet}
+</IconButton>