feat: full dark mode with :root.dark and dark: classes

layout.css
- Change .dark → :root.dark so variable overrides match Tailwind's
  :root, :host specificity and actually take effect
- Add global dark mode styles for input/select/textarea elements

All .svelte files:
- bg-white → bg-white dark:bg-gray-100 (cards, tables, containers)
- text-white → text-white dark:text-gray-950 (button text)
- Add dark:bg-gray-950 to main page containers (dashboard, account,
  license-keys, proclamations, proclamations/[id])
- Add dark:border-gray-300 to bordered elements (cards, tables, forms)
- Add dark:bg-gray-200 to secondary backgrounds (table headers,
  address form, price badges)
- Add dark:hover:bg-gray-300 / dark:hover:bg-gray-700 to hover states
  (sidebar nav links, clear button, admin categories table)

src/routes/(protected)/(user)/proclamations/[id]/+page.svelte

@@ -10,7 +10,7 @@
 	);
 </script>
 
-<div class="mx-auto flex h-full min-h-0 w-full max-w-3xl flex-col gap-6 p-6">
+<div class="mx-auto flex h-full min-h-0 w-full max-w-3xl flex-col gap-6 p-6 dark:bg-gray-950">
 	<a
 		href="/proclamations"
 		class="text-sm text-blue-600 hover:text-blue-800 hover:underline"
@@ -31,7 +31,7 @@
 				{data.proclamation.solfeggioFrequency.name}
 			</p>
 		</div>
-		<div class="rounded-lg border border-gray-200 bg-gray-50 px-4 py-2">
+		<div class="rounded-lg border border-gray-200 dark:border-gray-300 bg-gray-50 dark:bg-gray-200 px-4 py-2">
 			<p class="text-xs font-medium text-gray-500">Price</p>
 			<p class="text-sm font-semibold text-gray-900">
 				${data.proclamation.price.toFixed(2)}
@@ -39,7 +39,7 @@
 		</div>
 	</div>
 
-	<div class="prose max-w-none rounded-lg border border-gray-200 bg-white p-6">
+	<div class="prose max-w-none rounded-lg border border-gray-200 dark:border-gray-300 bg-white dark:bg-gray-100 p-6">
 		{@html data.proclamation.content}
 	</div>
 </div>