fix: do not override userConfig.server.origin when provided (#505)

Author: elthariel

vite-plugin-ruby/src/config.ts

@@ -90,7 +90,7 @@ function coerceConfigurationValues (config: ResolvedConfig, projectRoot: string,
   const server: ServerOptions = { fs, host: config.host, https, port, strictPort: true }
 
   if (booleanOption(config.skipProxy))
-    server.origin = `${https ? 'https' : 'http'}://${config.host}:${config.port}`
+    server.origin = userConfig.server?.origin || `${https ? 'https' : 'http'}://${config.host}:${config.port}`
 
   // Connect directly to the Vite dev server, rack-proxy does not proxy websocket connections.
   const hmr = userConfig.server?.hmr ?? {}