fix(mobile): overflow breaks — tables, composer, call bar, previews, cards (M1)

Mobile-audit batch 1. All fixes reuse cinny's own responsive primitives and are
mobile-gated so desktop is unchanged.

- Message tables: wrap <table> in an overflow-x container so a wide table scrolls
  instead of overflowing the message column / page body.
- Composer toolbar: let the before|editable|after row and the toolbar wrap on
  phones (@media <=750px) instead of squeezing the editable to zero and pushing
  Send off-screen.
- In-call control bar: collapse to the compact/stacked layout on a mobile
  viewport (ScreenSize.Mobile) too, not just when the bar's own container is
  <500px — fixes the 500-750px band where the control row overflowed.
- URL-preview card: base width toRem(400) -> min(25rem, 92vw) so a single card
  fits a narrow phone (still exactly 400px on desktop).
- Explore card grid: drop to one column at <=750px (was a fixed 3-col grid).

Two review passes: desktop behavior provably unchanged (all gated by @media /
ScreenSize.Mobile; the table wrapper only contains previously-overflowing tables).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/call/CallControls.tsx

@@ -35,6 +35,7 @@ import { useSetting } from '../../state/hooks/settings';
 import { settingsAtom } from '../../state/settings';
 import { callEmbedAtom } from '../../state/callEmbed';
 import { useResizeObserver } from '../../hooks/useResizeObserver';
+import { ScreenSize, useScreenSize } from '../../hooks/useScreenSize';
 import { stopPropagation } from '../../utils/keyboard';
 import { AsyncStatus, useAsyncCallback } from '../../hooks/useAsyncCallback';
 import { useCallEmbedRef } from '../../hooks/useCallEmbed';
@@ -51,18 +52,25 @@ export function CallControls({ callEmbed }: CallControlsProps) {
   const controlRef = useRef<HTMLDivElement>(null);
   const callEmbedRef = useCallEmbedRef();
   const setCallEmbed = useSetAtom(callEmbedAtom);
-  const [compact, setCompact] = useState(document.body.clientWidth < 500);
+  const screenSize = useScreenSize();
+  const [narrowContainer, setNarrowContainer] = useState(document.body.clientWidth < 500);
   const [isFullscreen, setIsFullscreen] = useState(false);
 
   useResizeObserver(
     useCallback(() => {
       const element = controlRef.current;
       if (!element) return;
-      setCompact(element.clientWidth < 500);
+      setNarrowContainer(element.clientWidth < 500);
     }, []),
     useCallback(() => controlRef.current, []),
   );
 
+  // Collapse to the stacked/compact layout whenever the bar's own container is
+  // narrow (a small desktop call window) OR the viewport is a phone. The old
+  // element-only `< 500` check left the ~11-control row overflowing off-screen
+  // in the 500–750px band (landscape phones / small tablets).
+  const compact = narrowContainer || screenSize === ScreenSize.Mobile;
+
   useEffect(() => {
     const onFullscreenChange = () => setIsFullscreen(!!document.fullscreenElement);
     document.addEventListener('fullscreenchange', onFullscreenChange);