feat: Implement sidebar toggle functionality and enhance Monthly Timesheet summary view

Components/Layout/MainLayout.razor.css

@@ -6,6 +6,7 @@
 
 main {
     flex: 1;
+    min-width: 0;
 }
 
 .sidebar {
@@ -36,6 +37,27 @@ main {
         text-overflow: ellipsis;
     }
 
+.sidebar-toggle {
+    display: none;
+    align-items: center;
+    justify-content: center;
+    flex-direction: column;
+    gap: 0.2rem;
+    width: 2.5rem;
+    height: 2.5rem;
+    margin-right: auto;
+    border: 1px solid #d6d5d5;
+    border-radius: 0.65rem;
+    background: #fff;
+}
+
+.sidebar-toggle-bar {
+    width: 1rem;
+    height: 2px;
+    background: #334155;
+    border-radius: 999px;
+}
+
 @media (max-width: 640.98px) {
     .top-row {
         justify-content: space-between;
@@ -56,6 +78,9 @@ main {
         height: 100vh;
         position: sticky;
         top: 0;
+        transition: width 0.2s ease;
+        overflow: hidden;
+        flex: 0 0 auto;
     }
 
     .top-row {
@@ -74,6 +99,14 @@ main {
         padding-left: 2rem !important;
         padding-right: 1.5rem !important;
     }
+
+    .sidebar-toggle {
+        display: inline-flex;
+    }
+
+    .sidebar.sidebar-collapsed {
+        width: 5rem;
+    }
 }
 
 #blazor-error-ui {