fix(web): clarify landing CTA copy for new users

The "Get Started" button drops users straight into the shared Dex flow,
which has no separate "register" option — registration completes
automatically after first login. Users new to Tapir had no signal that
signing in is also how they sign up. Reword the sub-text to say so
explicitly, keeping the single Dex CTA (sign-in and sign-up are one flow).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/web/views.templ

@@ -59,7 +59,7 @@ templ WelcomePage(user User, loggedIn bool) {
 				<div class="welcome-cta">
 					<a class="btn btn-lg" href="/auth/login">Get Started</a>
 				</div>
-				<p class="welcome-sub">Already have an account? You'll go straight through.</p>
+				<p class="welcome-sub">New to Tapir? Just sign in — you'll complete a quick setup right after. Already have an account? You'll go straight through.</p>
 			}
 		</section>
 	}