fix(ui): left-align admin sidebar — fix justify-content and text-align

Changed details.toggleable-item summary from justify-content:
space-between to gap + margin-left: auto on the chevron. Added
.flex-container-nav .item rule to force left alignment on all
menu items including standalone links.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web_src/css/shared/settings.css

@@ -9,8 +9,8 @@ details.toggleable-item .menu {
 
 details.toggleable-item summary {
   display: flex;
-  justify-content: space-between;
   align-items: center;
+  gap: 0.5em;
   padding: 0.92857143em 1.14285714em;
 }
 
@@ -20,6 +20,7 @@ details.toggleable-item summary::-webkit-details-marker /* Safari */ {
 }
 
 details.toggleable-item summary::after {
+  margin-left: auto;
   transition: transform 0.25s ease;
   content: "";
   width: 14px;
@@ -35,3 +36,8 @@ details.toggleable-item summary::after {
 details.toggleable-item[open] summary::after {
   transform: rotate(90deg);
 }
+
+.flex-container-nav .ui.menu .item {
+  text-align: left !important;
+  justify-content: flex-start !important;
+}