fix: add aria-label and visible text to search button for accessibility

Agent-Logs-Url: https://github.com/dsaub/proyecto-final/sessions/d1c1f40a-b3a3-4c18-98f9-be267a4a043b

Co-authored-by: dsaub <54474838+dsaub@users.noreply.github.com>

tienda/templates/tienda/base.html

@@ -108,7 +108,7 @@
                 <form class="search-suggestions-container" method="GET" action="{% url 'search' %}" role="search" id="searchForm">
                     <div class="input-group">
                         <input class="form-control" type="search" name="q" id="searchInput" placeholder="Buscar productos..." aria-label="Buscar" autocomplete="off">
-                        <button class="btn btn-outline-primary" type="submit">🔍</button>
+                        <button class="btn btn-outline-primary" type="submit" aria-label="Buscar productos">🔍 Buscar</button>
                     </div>
                     <div class="search-suggestions" id="searchSuggestions"></div>
                 </form>