Reverts Express server setup for the buzzer, migrates all functionality to a Bun server, and updates the workflow to execute the Bun server directly. Replit-Commit-Author: Agent Replit-Commit-Session-Id: f3ac8eb3-f610-4678-ab6e-ebf900098be4 Replit-Commit-Checkpoint-Type: full_checkpoint Replit-Commit-Event-Id: c1942b0a-0cf4-4ca9-9b5f-f80287c102f2 Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/d4b7863b-f7b2-425c-a9b5-ad7bd1885e9d/f3ac8eb3-f610-4678-ab6e-ebf900098be4/N1qS6qo Replit-Helium-Checkpoint-Created: true