feat: Implementa cor personalizada para a barra lateral

- Reverte a alteração da cor da classe `bg-gradient-primary` em `css/sb-admin-2.css` para o original.
- Adiciona a classe `sidebar-custom-color` em `css/main.css` com a cor `#343C40`.
- Aplica a nova classe `sidebar-custom-color` no elemento `<ul>` em `inc/sidebar.php`.

css/main.css

@@ -140,4 +140,8 @@ table.table-mini > tfoot > tr > th:first-child {
 
 table.table-mini > tbody > tr > td:not(:first-child) {
     min-width: 15px;
-}
+}
+.sidebar-custom-color {
+    background-color: #343C40 !important;
+    background-image: none !important;
+}

css/sb-admin-2.css

@@ -9863,8 +9863,8 @@ a:focus {
 }
 
 .bg-gradient-primary {
-  background-color: #343C40;
-  background-image: linear-gradient(180deg, #343C40 10%, #224abe 100%);
+  background-color: #4e73df;
+  background-image: linear-gradient(180deg, #4e73df 10%, #224abe 100%);
   background-size: cover;
 }
 

inc/sidebar.php

@@ -1,5 +1,5 @@
 <!-- Sidebar -->
-<ul class="navbar-nav bg-gradient-primary sidebar sidebar-dark accordion" id="accordionSidebar">
+<ul class="navbar-nav sidebar-custom-color sidebar sidebar-dark accordion" id="accordionSidebar">
 
     <!-- Sidebar - Brand -->
     <a class="sidebar-brand d-flex align-items-center justify-content-center" href="home" target="_top">