unify single user and multi user behaviour

site/astro.config.mjs

@@ -4,7 +4,10 @@ import svelte from "@astrojs/svelte";
 import tailwind from "@astrojs/tailwind";
 
 const env = loadEnv(process.env.NODE_ENV ?? 'development', process.cwd(), '');
-const serveTarget = env.PUBLIC_EDIT_URL || 'http://localhost:4041';
+// PUBLIC_EDIT_URL: non-empty → bincio edit URL; empty → proxy to bincio serve.
+// VITE_API_PORT lets `bincio dev` override the serve port without touching .env.
+const apiPort = process.env.VITE_API_PORT || '4041';
+const serveTarget = env.PUBLIC_EDIT_URL || `http://localhost:${apiPort}`;
 
 export default defineConfig({
   integrations: [svelte(), tailwind()],