Migrate to vite and some more stuff

- server: add a `Track` class
- server: add a create_track_class function
- client: migrate from vue-cli to vite

vite.config.js

@@ -0,0 +1,19 @@
+import { defineConfig } from "vite";
+import vue from "@vitejs/plugin-vue";
+const path = require("path");
+
+export default defineConfig({
+  plugins: [vue()],
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname, "src"),
+    },
+  },
+  css: {
+    preprocessorOptions: {
+      scss: {
+        additionalData: `@import "@/assets/css/_variables.scss";`,
+      },
+    },
+  },
+});