feat(theme): add complete theme support to all web apps

- ManaCore: add /themes page, use bg-background, add themeMode props
- ManaDeck: fix bg-gray to bg-background, add themeMode/onThemeModeChange
- Picture: add themeMode/onThemeModeChange props
- Zitare: add themeMode/onThemeModeChange props
- Presi: add themeMode/onThemeModeChange props

All apps now support:
- Theme variant dropdown (Lume, Ocean, Nature, Ember)
- Light/Dark/System mode selector
- Dynamic background colors via CSS variables

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/manacore/apps/web/src/routes/(app)/themes/+page.svelte

@@ -0,0 +1,19 @@
+<script lang="ts">
+	import { goto } from '$app/navigation';
+	import { ThemePage } from '@manacore/shared-theme-ui';
+	import { theme } from '$lib/stores/theme';
+</script>
+
+<svelte:head>
+	<title>Themes | ManaCore</title>
+</svelte:head>
+
+<ThemePage
+	currentVariant={theme.variant}
+	onSelectTheme={(v) => theme.setVariant(v)}
+	showModeSelector={true}
+	currentMode={theme.mode}
+	onModeChange={(m) => theme.setMode(m)}
+	showBackButton={true}
+	onBack={() => goto('/dashboard')}
+/>

apps/manadeck/apps/web/src/routes/(app)/+layout.svelte

@@ -18,7 +18,7 @@
 	let isCollapsed = $state(false);
 
 	// Get theme state
-	let effectiveMode = $derived(theme.effectiveMode);
+	let isDark = $derived(theme.isDark);
 
 	// Navigation items for ManaDeck
 	const navItems: PillNavItem[] = [
@@ -100,6 +100,10 @@
 		theme.toggleMode();
 	}
 
+	function handleThemeModeChange(mode: 'light' | 'dark' | 'system') {
+		theme.setMode(mode);
+	}
+
 	async function handleSignOut() {
 		await authStore.signOut();
 		goto('/login');
@@ -132,16 +136,16 @@
 <svelte:window onkeydown={handleKeydown} />
 
 {#if authStore.loading}
-	<div class="min-h-screen flex items-center justify-center bg-gray-50 dark:bg-gray-900">
+	<div class="min-h-screen flex items-center justify-center bg-background">
 		<div class="text-center">
 			<div
-				class="inline-block animate-spin h-8 w-8 border-4 border-primary-500 border-t-transparent rounded-full"
+				class="inline-block animate-spin h-8 w-8 border-4 border-primary border-t-transparent rounded-full"
 			></div>
-			<p class="mt-4 text-gray-500 dark:text-gray-400">Loading...</p>
+			<p class="mt-4 text-muted-foreground">Loading...</p>
 		</div>
 	</div>
 {:else if authStore.isAuthenticated}
-	<div class="min-h-screen bg-gray-50 dark:bg-gray-900">
+	<div class="min-h-screen bg-background">
 		<!-- Pill Navigation -->
 		<PillNavigation
 			items={navItems}
@@ -150,7 +154,7 @@
 			homeRoute="/decks"
 			onLogout={handleSignOut}
 			onToggleTheme={handleToggleTheme}
-			isDark={effectiveMode === 'dark'}
+			{isDark}
 			{isSidebarMode}
 			onModeChange={handleModeChange}
 			{isCollapsed}
@@ -159,6 +163,8 @@
 			showThemeVariants={true}
 			{themeVariantItems}
 			{currentThemeVariantLabel}
+			themeMode={theme.mode}
+			onThemeModeChange={handleThemeModeChange}
 			showLanguageSwitcher={false}
 			primaryColor="#6366f1"
 		/>

apps/picture/apps/web/src/routes/app/+layout.svelte

@@ -46,6 +46,10 @@
 		theme.toggleMode();
 	}
 
+	function handleThemeModeChange(mode: 'light' | 'dark' | 'system') {
+		theme.setMode(mode);
+	}
+
 	// Client-side auth check
 	$effect(() => {
 		if (authStore.initialized && !authStore.loading && !authStore.user) {
@@ -203,6 +207,8 @@
 				showThemeVariants={true}
 				{themeVariantItems}
 				{currentThemeVariantLabel}
+				themeMode={theme.mode}
+				onThemeModeChange={handleThemeModeChange}
 				showLanguageSwitcher={false}
 				primaryColor="#3b82f6"
 			/>

apps/presi/apps/web/src/routes/+layout.svelte

@@ -78,6 +78,10 @@
 		theme.toggleMode();
 	}
 
+	function handleThemeModeChange(mode: 'light' | 'dark' | 'system') {
+		theme.setMode(mode);
+	}
+
 	function handleLogout() {
 		auth.logout();
 		goto('/login');
@@ -167,6 +171,8 @@
 				showThemeVariants={true}
 				{themeVariantItems}
 				{currentThemeVariantLabel}
+				themeMode={theme.mode}
+				onThemeModeChange={handleThemeModeChange}
 				showLanguageSwitcher={false}
 				showLogout={true}
 				onLogout={handleLogout}

apps/zitare/apps/web/src/routes/+layout.svelte

@@ -107,6 +107,10 @@
 		theme.toggleMode();
 	}
 
+	function handleThemeModeChange(mode: 'light' | 'dark' | 'system') {
+		theme.setMode(mode);
+	}
+
 	async function handleLogout() {
 		await authStore.signOut();
 		goto('/login');
@@ -169,6 +173,8 @@
 			showThemeVariants={true}
 			{themeVariantItems}
 			{currentThemeVariantLabel}
+			themeMode={theme.mode}
+			onThemeModeChange={handleThemeModeChange}
 			showLanguageSwitcher={false}
 			showLogout={authStore.isAuthenticated}
 			onLogout={handleLogout}