Use import.meta.env.DEV to detect dev mode in astro.config.mjs

Agent-Logs-Url: https://github.com/DuendeSoftware/docs.duendesoftware.com/sessions/f321fe8e-8305-4101-9651-3af6d064ed4c

Co-authored-by: maartenba <485230+maartenba@users.noreply.github.com>

Author: Copilot

astro/astro.config.mjs

@@ -21,7 +21,7 @@ import markdownOutput from "./src/plugins/markdown-output.js";
 import contributorMapping from "./src/plugins/contributor-mapping.js";
 
 // https://astro.build/config
-const isDev = process.env.NODE_ENV !== "production";
+const isDev = import.meta.env.DEV;
 
 export default defineConfig({
   site: "https://docs.duendesoftware.com",