feat(landing): add to-calendar button on hero

src/components/AddToCalendar.astro

@@ -0,0 +1,56 @@
+---
+// TODO: replace with the public iCal URL of the DevFest 2026 calendar event.
+// Use `webcal://` scheme so most browsers hand off to the OS default calendar app
+// (Apple Calendar, Outlook desktop). Falls back to downloading the .ics file.
+const ICS_URL = 'webcal://example.com/devfest-cz-2026.ics';
+---
+
+<a class="add-to-calendar" href={ICS_URL}>
+	<span class="label">Add to calendar</span>
+	<span class="icon" aria-hidden="true">+</span>
+</a>
+
+<style lang="scss">
+	.add-to-calendar {
+		display: inline-flex;
+		align-items: center;
+		gap: 0.6rem;
+		font-family: 'Share Tech Mono', monospace;
+		font-size: 0.78rem;
+		letter-spacing: 0.28em;
+		text-transform: uppercase;
+		color: var(--color-text);
+		text-decoration: none;
+		background: transparent;
+		border: 1px solid rgba(204, 0, 0, 0.55);
+		padding: 0.85rem 2rem;
+		clip-path: polygon(8px 0%, 100% 0%, calc(100% - 8px) 100%, 0% 100%);
+		transition: background 0.25s, border-color 0.25s, color 0.25s;
+
+		&:hover {
+			background: rgba(204, 0, 0, 0.18);
+			border-color: rgba(204, 0, 0, 0.85);
+			color: var(--color-text);
+		}
+
+		&:focus-visible {
+			outline: 1px solid rgba(204, 0, 0, 0.85);
+			outline-offset: 3px;
+		}
+	}
+
+	.icon {
+		font-size: 1rem;
+		color: var(--color-accent);
+		opacity: 0.9;
+		line-height: 1;
+	}
+
+	@media (max-width: 600px) {
+		.add-to-calendar {
+			font-size: 0.72rem;
+			padding: 0.75rem 1.6rem;
+			letter-spacing: 0.22em;
+		}
+	}
+</style>

src/pages/index.astro

@@ -2,6 +2,7 @@
 import BaseLayout from '../layouts/BaseLayout.astro';
 import Countdown from '../components/Countdown';
 import NewsletterForm from '../components/NewsletterForm';
+import AddToCalendar from '../components/AddToCalendar.astro';
 import Footer from '../components/Footer.astro';
 import HeroBackground from '../components/HeroBackground.astro';
 import Ticker from '../components/Ticker.astro';
@@ -144,6 +145,9 @@ const tickerTopics = [
 					Leave your email and we'll let you know the moment tickets go on sale.
 				</p>
 				<NewsletterForm client:visible />
+				<div class="newsletter-calendar">
+					<AddToCalendar />
+				</div>
 			</div>
 		</section>
 	</main>

src/pages/index.scss

@@ -456,6 +456,12 @@
 		margin: 0 auto 2.6rem;
 	}
 
+	.newsletter-calendar {
+		margin-top: 1.75rem;
+		display: flex;
+		justify-content: center;
+	}
+
 	.section-label {
 		font-family: 'Share Tech Mono', monospace;
 		font-size: 0.78rem;