Update LanguageSelector and development page components for improved client behavior

- Changed LanguageSelectorComponent to use client:visible for better loading performance.
- Updated CollapsibleIntro and ContributionCalendar components to utilize client:visible, enhancing user experience by ensuring they load only when in view.

src/layouts/Layout.astro

@@ -74,7 +74,7 @@ const { language, textDirection } = I18N;
     <CookieBanner />
     <BackToTop />
     <!-- Start of Rocket.Chat Livechat Script -->
-    <script type="text/javascript">
+    <script type="text/javascript" defer>
       (function(w, d, s, u) {
         w.RocketChat = function(c) { w.RocketChat._.push(c) }; w.RocketChat._ = []; w.RocketChat.url = u;
         const h = d.getElementsByTagName(s)[0], j = d.createElement(s);