feat: migrate m3-atlas from MinIO to RustFS

- Replace minio.nix with rustfs.nix using rustfs-flake NixOS module
- Add rustfs flake input (github:rustfs/rustfs-flake)
- Reuse same ports (API: 3008, Console: 3007) and data dir (/var/storage/s3)
- Add separate agenix secrets for access-key and secret-key
- Keep Traefik routes unchanged (s3.m3tam3re.com, minio.m3tam3re.com)
- MinIO had 6 unfixed CVEs and is abandoned upstream

flake.nix

@@ -74,6 +74,11 @@
       flake = false;
     };
     hermes-agent.url = "github:NousResearch/hermes-agent/v2026.4.30";
+
+    rustfs = {
+      url = "github:rustfs/rustfs-flake";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs = {
@@ -127,6 +132,7 @@
           inputs.disko.nixosModules.disko
           agenix.nixosModules.default
           m3ta-nixpkgs.nixosModules.default
+          inputs.rustfs.nixosModules.rustfs
         ];
       };
       m3-kratos = nixpkgs.lib.nixosSystem {