fix(ui): keep the language switcher menu inside the viewport

The menu opens upwards from the sidebar footer and is a child of the
scrollable sidebar. On short windows it was taller than the space above
the trigger, so its top (the first entries) was clipped by the sidebar.

Cap the menu height to the viewport and let it scroll instead.

Signed-off-by: gangna2s-arch <281744444+gangna2s-arch@users.noreply.github.com>

core/http/react-ui/src/App.css

@@ -708,6 +708,12 @@
   bottom: calc(100% + 8px);
   left: 0;
   min-width: 220px;
+  /* The menu opens upwards from the sidebar footer, inside a scrollable
+     sidebar. Cap its height to the viewport so it stays within the sidebar
+     box instead of being clipped at the top on short windows. */
+  max-height: calc(100dvh - 64px);
+  overflow-y: auto;
+  overscroll-behavior: contain;
   background: var(--color-surface-float);
   border: 1px solid var(--color-border-card);
   border-radius: var(--radius-lg);