fix: UI/UX consistency overhaul — fix 8 bugs, standardize design system

Bug fixes:
- Backup refresh no longer re-renders entire page (separate refreshing state)
- SSL cert button no longer flickers when no certs available
- Volume mode selector rewritten to use proper scope system (7 scopes)
- Navigation flicker eliminated when returning from env/volumes pages
- Logout button moved to sidebar footer near theme/locale controls
- Subdomain pattern now shows variable hint tooltip ({project}, {stage}, etc.)
- SSL certificate selector moved to Credentials page with auto-save
- Projects page now has search/filter by name, image, or registry

Consistency improvements:
- New Breadcrumb component replaces 5 inline implementations
- New IconArrowLeft, IconChevronDown components replace inline SVGs
- All inline spinners replaced with IconLoader component
- 10 semantic badge classes with dark mode variants in tokens.css
- Global disabled button cursor-not-allowed rule
- Raw inputs in auth page replaced with FormField components
- Missing aria-labels added to icon-only buttons
- Error panels standardized to use design tokens

web/src/routes/proxies/+page.svelte

@@ -11,7 +11,7 @@
 	import ProxyGroup from '$lib/components/ProxyGroup.svelte';
 	import ProxyFilter from '$lib/components/ProxyFilter.svelte';
 	import EmptyState from '$lib/components/EmptyState.svelte';
-	import { IconGlobe, IconLoader } from '$lib/components/icons';
+	import { IconGlobe, IconLoader, IconPlus } from '$lib/components/icons';
 
 	let proxies = $state<ProxyView[]>([]);
 	let loading = $state(true);
@@ -144,9 +144,7 @@
 		href="/proxies/create"
 		class="inline-flex items-center gap-2 rounded-lg bg-[var(--color-brand-600)] px-4 py-2.5 text-sm font-medium text-white shadow-sm transition-all duration-150 hover:bg-[var(--color-brand-700)] active:animate-press"
 	>
-		<svg class="h-4 w-4" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-			<path d="M5 12h14" /><path d="M12 5v14" />
-		</svg>
+		<IconPlus size={16} />
 		{$t('proxies.create')}
 	</a>
 </div>
@@ -158,14 +156,9 @@
 		<span class="ml-2 text-sm text-[var(--text-secondary)]">{$t('common.loading')}</span>
 	</div>
 {:else if error}
-	<!-- Error state -->
-	<div class="rounded-xl border border-red-200 bg-red-50 p-6 text-center dark:border-red-900 dark:bg-red-950">
-		<p class="text-sm text-red-700 dark:text-red-300">{error}</p>
-		<button
-			type="button"
-			onclick={loadProxies}
-			class="mt-3 rounded-lg bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-700 transition-colors"
-		>
+	<div class="rounded-xl border border-[var(--color-danger-light)] bg-[var(--color-danger-light)] p-4">
+		<p class="text-sm text-[var(--color-danger)]">{error}</p>
+		<button type="button" class="mt-2 text-sm font-medium text-[var(--color-danger)] underline hover:no-underline" onclick={loadProxies}>
 			{$t('common.retry')}
 		</button>
 	</div>