Add app version definition in Vite configuration using environment variable or package version

vite.config.ts

@@ -1,6 +1,16 @@
 import { sveltekit } from '@sveltejs/kit/vite';
 import { defineConfig } from 'vite';
+import pkg from './package.json' with { type: 'json' };
+
+declare const process: {
+	env: Record<string, string | undefined>;
+};
+
+const appVersion = process.env.VITE_APP_VERSION ?? pkg.version ?? 'dev';
 
 export default defineConfig({
+	define: {
+		__APP_VERSION__: JSON.stringify(appVersion),
+	},
 	plugins: [sveltekit()],
 });