Add modular service configuration with SearXNG and Nginx

- Create modules/ directory with reusable NixOS modules
- Add system module for main user configuration
- Add podman module for rootless container support
- Add nginx module with automatic Let's Encrypt SSL
- Add searxng module with Anubis AI firewall protection
- Configure SearXNG at search.ashisgreat.xyz
- Enable nginx reverse proxy with HTTPS

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

flake.nix

@@ -12,6 +12,7 @@
       system = "x86_64-linux";
       modules = [
         ./configuration.nix
+        ./modules
         sops-nix.nixosModules.sops
       ];
     };