feat(ui): implementar selector de vista universal (tabla/grilla vs tarjetas/mosaico) con persistencia

app/templates/partials/view_switcher.html

@@ -0,0 +1,21 @@
+{# Componente reutilizable: Selector de vista (Tabla / Grilla vs. Tarjetas / Mosaico) #}
+<div class="btn-group btn-group-sm shadow-sm view-switcher-group" 
+     role="group" 
+     aria-label="{% trans %}Selector de Vista{% endtrans %}" 
+     data-context="{{ context_id|default('default') }}"
+     data-default-view="{{ default_view|default('cards') }}">
+    <button type="button" 
+            class="btn btn-outline-secondary view-switcher-btn" 
+            data-view="table" 
+            title="{% trans %}Vista de Tabla / Grilla (filas, columnas y análisis denso){% endtrans %}">
+        <i class="bi bi-table me-1"></i>
+        <span class="d-none d-sm-inline">{% trans %}Tabla{% endtrans %}</span>
+    </button>
+    <button type="button" 
+            class="btn btn-outline-secondary view-switcher-btn" 
+            data-view="cards" 
+            title="{% trans %}Vista de Tarjetas / Mosaico (amigable, visual y responsive){% endtrans %}">
+        <i class="bi bi-grid-fill me-1"></i>
+        <span class="d-none d-sm-inline">{% trans %}Tarjetas{% endtrans %}</span>
+    </button>
+</div>