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/configure.html

@@ -16,7 +16,7 @@
                     <div class="card-header">{'Configuration'|t}</div>
                     <div class="card-body">
                         <div class="form-group">
-                            <label class="form-label" for="title">Shaarli {'title'|t}</label>
+                            <label class="form-label" for="title">{'Shaarli title'|t}</label>
                             <input type="text" name="title" id="title" class="form-control" value="{$title}" />
                         </div>
                         <div class="form-group">
@@ -122,7 +122,7 @@
                         <div class="filter-toggle-row">
                             <div>
                                 <div class="filter-toggle-label">{'RSS direct links'|t}</div>
-                                <div class="sublabel">Enabling it will show a permalink in the description.</div>
+                                <div class="sublabel">{'Enabling it will show a permalink in the description.'|t}</div>
                             </div>
                             <label class="toggle-switch">
                                 <input type="checkbox" name="enableRssPermalinks" id="enableRssPermalinks" {if="$enable_rss_permalinks"}checked{/if}/>