Refactor toast notifications and modal dialog implementation

- Updated SCSS for toast notifications to support multiple toast types (success, info, warning, error) and improved layout.
- Added new SVG icons for error, info, success, and warning notifications.
- Created separate HTML templates for toast notifications and modal dialogs.
- Enhanced the dev panel with buttons to test different toast notifications and modal dialogs.

backend/templates/base.html

@@ -23,15 +23,8 @@
             dispatchEvent(new CustomEvent("TrunkApplicationStarted", {detail: {wasm}}));
         </script>
 
-        <div id="toasts">
-            <div id="toast"></div>
-        </div>
-
-        <dialog id="modal-dialog">
-            <div class="content"></div>
-            <input type="button" class="ok" value="OK">
-            <input type="button" class="cancel" value="Cancel">
-        </dialog>
+        {% include "toast.html" %}
+        {% include "modal_dialog.html" %}
 
         {% block body_container %}{% endblock %}