Feat: Add AgentSidebar #3221 (#5296)

### What problem does this PR solve?

Feat: Add AgentSidebar #3221

### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/components/hooks/use-mobile.tsx

@@ -0,0 +1,21 @@
+import * as React from 'react';
+
+const MOBILE_BREAKPOINT = 768;
+
+export function useIsMobile() {
+  const [isMobile, setIsMobile] = React.useState<boolean | undefined>(
+    undefined,
+  );
+
+  React.useEffect(() => {
+    const mql = window.matchMedia(`(max-width: ${MOBILE_BREAKPOINT - 1}px)`);
+    const onChange = () => {
+      setIsMobile(window.innerWidth < MOBILE_BREAKPOINT);
+    };
+    mql.addEventListener('change', onChange);
+    setIsMobile(window.innerWidth < MOBILE_BREAKPOINT);
+    return () => mql.removeEventListener('change', onChange);
+  }, []);
+
+  return !!isMobile;
+}