fix(ui): left-align all admin sidebar menu items

Fomantic UI's vertical menu centers text by default. Added
text-align: left to .flex-container-nav menu items so all
admin sidebar entries align consistently.

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

web_src/css/modules/flexcontainer.css

@@ -11,6 +11,10 @@
   width: 240px;
 }
 
+.flex-container-nav .ui.menu .item {
+  text-align: left;
+}
+
 /* wide sidebar on the right, used in frontpage */
 .flex-container-sidebar {
   width: 35%;

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;
 }
 
@@ -20,7 +20,6 @@ details.toggleable-item summary::-webkit-details-marker /* Safari */ {
 }
 
 details.toggleable-item summary::after {
-  margin-left: auto;
   transition: transform 0.25s ease;
   content: "";
   width: 14px;
@@ -36,8 +35,3 @@ 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;
-}