Refactor Docker setup and frontend structure

- Updated Dockerfile to copy frontend files to meshchatx/public directory.
- Modified .dockerignore to include meshchatx/public.
- Added a new script to prepare the frontend directory.
- Adjusted Vite configuration to output to the new public directory.
- Updated GitHub Actions workflow to reflect changes in build process and artifact handling.

scripts/prepare_frontend_dir.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+from pathlib import Path
+import shutil
+
+TARGET = Path("meshchatx") / "public"
+
+if TARGET.exists():
+    shutil.rmtree(TARGET)
+
+TARGET.mkdir(parents=True, exist_ok=True)
+