Update searchbar placeholder with record count

* Searchbar now includes total record count in its placeholder
* Style enhancements to make placeholder text more noticeable

invenio_theme_tuw/theme/assets/semantic-ui/less/invenio_theme_tuw/theme/globals/site.overrides

@@ -100,6 +100,11 @@ h3.smaller-text {
   max-width: 80vw;
 }
 
+#searchbar input::placeholder { 
+  font-weight: bold;
+  opacity: 1;
+}
+
 .features-wrapper {
   display: flex;
   justify-content: space-evenly;

invenio_theme_tuw/theme/templates/semantic-ui/invenio_theme_tuw/search_bar.html

@@ -10,7 +10,7 @@
 <form action="{{ config.THEME_SEARCH_ENDPOINT }}">
   <div class="ui action input" id="searchbar">
     <label class="invisible" for="q">Search Query</label>
-    <input class="huge" id="q" name="q" placeholder="Type and press enter to search..." type="text">
+    <input class="huge" id="q" name="q" placeholder="Search {{ record_count() }} records..." type="text">
     <button class="ui icon button huge" type="submit" aria-label="submit query">
       <i class="search icon"></i>
     </button>

invenio_theme_tuw/views.py

@@ -147,6 +147,10 @@ def create_blueprint(app):
 
         return metadata
 
+    @blueprint.app_template_global("record_count")
+    def record_count():
+        return FrontpageRecordsSearch().count()
+
     @blueprint.route("/")
     def tuw_index():
         """Custom landing page showing the latest 5 records."""