Make sequoia-subscribe cookie Secure

Fixes issue #21

packages/cli/src/components/sequoia-subscribe.js

···
 		const expires = new Date(
 			Date.now() + 365 * 24 * 60 * 60 * 1000,
 		).toUTCString();
-		document.cookie = `sequoia_did=${encodeURIComponent(did)}; expires=${expires}; path=/; SameSite=Lax`;
+		document.cookie = `sequoia_did=${encodeURIComponent(did)}; Expires=${expires}; Path=/; SameSite=Lax; Secure`;
 	} catch {
 		// Cookie write may fail in some embedded contexts
 	}
···
 function clearSubscriberDid() {
 	try {
 		document.cookie =
-			"sequoia_did=; expires=Thu, 01 Jan 1970 00:00:00 GMT; path=/; SameSite=Lax";
+			"sequoia_did=; Expires=Thu, 01 Jan 1970 00:00:00 GMT; Path=/; SameSite=Lax; Secure";
 	} catch {
 		// ignore
 	}