fix: replace CSS variable inversion with standard Tailwind dark: classes

The :root.dark CSS variable inversion caused contrast problems -
text-gray-900 and bg-gray-950 both became light in dark mode, making
text invisible on backgrounds.

Fix:
- Remove :root.dark { --color-gray-*: ... } block from layout.css
- Change :root.dark selector to .dark for form element styles
- Add standard Tailwind dark: classes throughout every .svelte page
  - dark:bg-gray-950 (page backgrounds)
  - dark:bg-gray-900 (card/surface backgrounds)
  - dark:bg-gray-800 (table headers, elevated surfaces, active nav links)
  - dark:bg-gray-700 (primary buttons)
  - dark:text-gray-100 (primary text)
  - dark:text-gray-300 (secondary text, labels)
  - dark:text-gray-400 (muted text, inactive nav links, links)
  - dark:border-gray-700 (borders)
  - dark:border-gray-600 (input borders)
  - dark:hover:bg-gray-800 (sidebar hover)
  - dark:hover:bg-gray-600 (button hover)
  - dark:prose-invert (rich text content)
- TopBar: full dark mode support (bg, links, toggle button)
- Sidebar: all nav links, active states, admin submenu get dark mode
- Auth pages (login, register, forgot, reset): full dark mode
- Protected pages (dashboard, account, setup, license-keys,
  proclamations, categories): full dark mode
- Home page, error page, admin page: dark:text-gray-100

src/lib/components/ui/topBar/TopBar.svelte

@@ -25,25 +25,26 @@
 	}
 </script>
 
-<nav class="flex w-full items-center justify-between px-8 py-6">
-	<span><a href="/">Rhema Wave Technologies</a></span>
+<nav class="flex w-full items-center justify-between border-b border-gray-200 px-8 py-6 dark:border-gray-700 dark:bg-gray-950 dark:text-gray-100">
+	<span><a href="/" class="dark:text-gray-100">Rhema Wave Technologies</a></span>
 	<div class="flex items-center gap-4">
-		<button onclick={toggleTheme} class="border px-3 py-1 text-sm">
+		<button onclick={toggleTheme} class="border border-gray-300 px-3 py-1 text-sm dark:border-gray-600 dark:text-gray-300">
 			{dark ? 'Light' : 'Dark'}
 		</button>
 		{#if $session.data}
 			{#if isAdmin}
-				<a href="/admin">Admin Panel</a>
+				<a href="/admin" class="dark:text-gray-300 dark:hover:text-gray-100">Admin Panel</a>
 			{/if}
-			<a href="/dashboard">Dashboard</a>
+			<a href="/dashboard" class="dark:text-gray-300 dark:hover:text-gray-100">Dashboard</a>
 			<button
+				class="dark:text-gray-300 dark:hover:text-gray-100"
 				onclick={async () => {
 					await authClient.signOut();
 					window.location.href = '/';
 				}}>Log Out</button
 			>
 		{:else}
-			<span><a href="/login">Log In</a> | <a href="/register">Register</a></span>
+			<span class="dark:text-gray-300"><a href="/login" class="dark:text-gray-300 dark:hover:text-gray-100">Log In</a> | <a href="/register" class="dark:text-gray-300 dark:hover:text-gray-100">Register</a></span>
 		{/if}
 	</div>
 </nav>