feat(ui): elegant wedding white/silver/gold redesign

Reskin the whole app via design tokens in tailwind-theme.css (remapped
color ramps) plus a define-once component layer in lib/styles/components.css
(.btn, .card, .input, .chip, .badge, .sheet, …). Buttons are muted/outlined
gold rather than flat fills. Self-host Inter + Fraunces (woff2) under the
existing font-src 'self' CSP. Restyle the shared components and the account,
admin, host, join, recover and upload screens against the new tokens.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/components/Modal.svelte

@@ -49,9 +49,7 @@
 			use:focusTrap={{ onclose: onClose }}
 			use:scrollLock
 		>
-			<div
-				class="pointer-events-auto w-full max-w-sm rounded-2xl bg-white p-6 shadow-xl dark:bg-gray-900"
-			>
+			<div class="card pointer-events-auto w-full max-w-sm p-6 shadow-xl">
 				{@render children()}
 			</div>
 		</div>