AirDrop-style cross-platform file transfer app with radar UI

GOAL: Build "Hop": an AirDrop-style app to send files between a Mac and a Windows PC on the same Wi-Fi. MOTION: No cloud, no accounts. Stack: Electron (one codebase for macOS + Windows), plain HTML/CSS/JS UI, no frameworks. 1. Discovery: each device broadcasts a small JSON beacon over UDP (port 47800) every 1.5 s to every subnet broadcast address. Show peers that were seen in the last 10 s. Ignore your own beacons. 2. Transfer: each device runs an HTTP server on a random port. Sender POSTs an offer (file names + sizes), the receiver shows Accept / Decline, then files stream one by one. Support whole folders. Never overwrite: "photo (1).jpg". Reject any path that could escape the download folder. 3. Trust: an "Always accept from this device" checkbox. Save to Downloads/Hop (changeable). 4. Before building any UI, write a Node test where two devices in one process find each other and send a folder + a 3 MB file; compare hashes. 5. UI, Apple-level polish: a radar with this device in the center and peers around it (Apple logo on Macs, Windows logo on PCs). Drag files onto a peer, or click it to pick files. The file chip flies along an arc into the peer, then an iOS 17 NameDrop-style iridescent light wave sweeps across the window (WebGL shader with a Canvas fallback). Progress ring around the peer. Vibrancy on macOS, acrylic on Windows 11. Light / Dark / Auto switch. 6. Icon: macOS squircle, 1024 px, readable at 16 px. Draw 3 concepts, compare them, keep the best. 7. Run independent review passes on the UI and the networking code before shipping. 8. GitHub Actions: on a v* tag build Hop-mac-arm64.dmg, Hop-mac-x64.dmg and Hop-windows-x64.exe and publish a release. 9. Add a startup log and always show the window, so a launch that hangs is easy to debug. Ship it, then give me the install steps for both machines.