Add shared building-block components: header, footer, CTAs, topographic background

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/CTAButtons.astro

@@ -0,0 +1,47 @@
+---
+import { getAuthConfig } from '../config/auth';
+
+interface Props {
+  variant?: 'primary' | 'inverted';
+  size?: 'md' | 'lg';
+  showSecondary?: boolean;
+  primaryLabel?: string;
+  secondaryLabel?: string;
+  secondaryHref?: string;
+}
+
+const auth = getAuthConfig();
+
+const {
+  variant = 'primary',
+  size = 'md',
+  showSecondary = true,
+  primaryLabel = 'Start free trial',
+  secondaryLabel = 'Sign in',
+  secondaryHref = auth.signInUrl,
+} = Astro.props;
+
+const padY = size === 'lg' ? 'py-3' : 'py-2';
+const padX = size === 'lg' ? 'px-6' : 'px-5';
+const fontSize = size === 'lg' ? 'text-base' : 'text-sm';
+---
+<div class="flex flex-wrap items-center gap-3">
+  <a
+    href={auth.signUpUrl}
+    class={`inline-flex items-center justify-center rounded ${padX} ${padY} ${fontSize} font-semibold transition-colors
+      ${variant === 'primary'
+        ? 'bg-accent text-bg hover:bg-accent-muted focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:ring-offset-bg'
+        : 'bg-bg text-accent border border-accent hover:bg-accent hover:text-bg'
+      }`}
+  >
+    {primaryLabel}
+  </a>
+  {showSecondary && (
+    <a
+      href={secondaryHref}
+      class={`inline-flex items-center justify-center rounded ${padX} ${padY} ${fontSize} font-medium text-text border border-border-strong hover:border-accent hover:text-accent transition-colors`}
+    >
+      {secondaryLabel}
+    </a>
+  )}
+</div>