feat(frontend): darken neutral theme and reorder theme switcher

- make neutral theme a warm dark graphite
- order switches as dark -> neutral -> light -> system
- replace neutral icon with contrast glyph

frontend/src/lib/components/ThemeSwitcher.svelte

@@ -4,9 +4,9 @@
 	import { theme, type Theme } from '$lib/stores/theme.svelte';
 
 	const options: { value: Theme; label: string; icon: IconName }[] = [
-		{ value: 'light', label: 'Light', icon: 'light_mode' },
 		{ value: 'dark', label: 'Dark', icon: 'dark_mode' },
-		{ value: 'neutral', label: 'Neutral', icon: 'palette' },
+		{ value: 'neutral', label: 'Neutral', icon: 'contrast' },
+		{ value: 'light', label: 'Light', icon: 'light_mode' },
 		{ value: 'system', label: 'System', icon: 'brightness_auto' }
 	];
 </script>