Add asset pipeline and professionalize theme

Introduce a Node build system for minified CSS/JS with content hashes,
add PWA support, i18n helpers, accessibility improvements, and more
translatable strings. Move theme configuration from bookmarks to
localStorage, add Playwright tests, and set up CI workflows.

shaarli-pro/pluginsadmin.html

@@ -14,7 +14,7 @@
             </noscript>
 
             <h1>{'Plugin administration'|t}</h1>
-            <p>Drag and drop your plugin to change the order in which they'll be called. Uncheck enabled plugin to disable them and vice-versa.</p>
+            <p>{'Drag and drop your plugin to change the order in which they will be called. Uncheck an enabled plugin to disable it and vice-versa.'|t}</p>
 
             <form action="{$base_path}/admin/plugins" method="post">
                 <input type="hidden" name="token" value="{$token}">