fix: prevent copy button label from shifting table

docs/PLAN.md

@@ -22,3 +22,4 @@ Updated: 2026-04-01
 6. Moved user creation into a modal flow and tightened the operator UX with quieter navigation and a denser users table.
 7. Rebuilt the UI shell from scratch around a stable topbar/tab layout with fixed typography and lower visual noise across window sizes.
 8. Corrected the user-creation flow to select a 3proxy service instead of assigning a per-user port, matching the documented 3proxy model.
+9. Stabilized the Users table copy action so the column no longer shifts when the button label changes to `Copied`.

src/app.css

@@ -150,6 +150,13 @@ button,
   color: var(--text);
 }
 
+.copy-button {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  min-width: 76px;
+}
+
 .copy-button.danger {
   color: var(--danger);
 }