Switch to bun and add deploy script

Update engines in package.json to bun, switch all justfile recipes from npm to bun, add scripts/deploy.sh for production deployment.

scripts/deploy.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+set -e
+
+APP_NAME="tietokonepaja-fi"
+APP_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+DEPLOY_DIR="/var/www/tietokonepaja-fi"
+
+echo "Deploying $APP_NAME from $APP_DIR..."
+
+cd "$APP_DIR"
+
+echo "Pulling latest changes..."
+sudo -E git pull
+
+echo "Installing dependencies..."
+sudo bun install
+
+echo "Building application..."
+sudo bun run build
+
+echo "Copying to $DEPLOY_DIR..."
+sudo cp -r dist/. "$DEPLOY_DIR"
+
+echo "Deployment complete."