Fix Docker deployment and runtime environment variables

- Add --break-system-packages flag to pip install for Alpine Linux 3.12+ compatibility
- Configure Astro server to bind to 0.0.0.0 for Docker container accessibility
- Replace import.meta.env with process.env for runtime environment variable access in SSR
- Enable dynamic LOGIN configuration at runtime

Co-Authored-By: Warp <agent@warp.dev>

src/components/DownloadForm.astro

@@ -1,7 +1,7 @@
 ---
 import { t } from "../lib/i18n";
 
-const streamOnly = import.meta.env.STREAM_ONLY === "true";
+const streamOnly = process.env.STREAM_ONLY === "true";
 ---
 
 <div class="container mx-auto px-4 py-8 max-w-2xl">