Add core UI components and layout for media platform

Initializes the client-side application with fundamental UI components, including navigation, cards for articles and auctions, and various elements for user interaction and display.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 069d4324-6c40-4355-955e-c714a50de1ea
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/3df548ff-50ae-432f-9be4-25d34eccc983/069d4324-6c40-4355-955e-c714a50de1ea/bVdKIaU

client/src/hooks/use-mobile.tsx

@@ -0,0 +1,19 @@
+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
+}