B-217: show full header username without 108px truncation

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

frontend/shared/auth.css

@@ -472,11 +472,11 @@
 }
 
 .account-button > span {
-  min-width: 0px;
+  flex: 0 0 auto;
 
-  overflow: hidden;
+  min-width: max-content;
 
-  text-overflow: ellipsis;
+  overflow: visible;
 
   white-space: nowrap;
 }
@@ -1028,11 +1028,15 @@ button.account-role-badge:focus-visible {
 
     display: grid;
 
-    grid-template-columns: auto minmax(0px, 1fr);
+    grid-template-columns: minmax(0px, 1fr);
   }
 
   .account-menu-shell .account-button {
+    width: 100%;
+
     min-width: 0px;
+
+    max-width: none;
   }
 
   .account-dropdown {
@@ -1179,7 +1183,7 @@ button.account-role-badge:focus-visible {
   gap: 3px;
 }
 
-@media (min-width: 1280px) {
+@media (min-width: 1280px) and (max-width: 1439px) {
   .app-header .header-command-group .account-role-badge span {
     display: none;
   }
@@ -1191,17 +1195,25 @@ button.account-role-badge:focus-visible {
 
     padding-inline: 6px;
   }
+}
 
+@media (min-width: 1280px) {
   .header-command-group .account-button {
+    flex: 0 0 auto;
+
     width: auto;
 
-    max-width: 108px;
+    max-width: none;
+
+    overflow: visible;
 
     padding: 0px 8px;
   }
 
   .header-command-group .account-button > span {
     display: inline;
+
+    overflow: visible;
   }
 }
 
@@ -1264,11 +1276,11 @@ button.account-role-badge:focus-visible {
 }
 
 .account-button {
-  overflow: hidden;
+  flex: 0 0 auto;
 
-  text-overflow: ellipsis;
+  overflow: visible;
 
-  max-width: 108px;
+  max-width: none;
 
   min-height: 28px;