chore(modules): drop the riscv64 module, which belongs to nixos-config-sbc

Nothing imported it and the riscv64 output was already commented out; riscv64 hosts live in ryan4yin/nixos-config-sbc.

Assisted-by: DeepSeek Harness 0.2.1-rc.2 (deepseek-flash)

modules/README.md

@@ -63,7 +63,6 @@ modules/
         ├── qemu-guest-hardware-configuration.nix
         ├── qemu-guest.nix  # VM guest base module (libvirt/QEMU guests)
         ├── server-aarch64.nix
-        ├── server-riscv64.nix # module only; the riscv64 output is disabled
         └── server.nix
 ```
 

modules/nixos/server/server-riscv64.nix

@@ -1,24 +0,0 @@
-{ lib, ... }:
-{
-  # =========================================================================
-  #      Base NixOS Configuration
-  # =========================================================================
-
-  imports = [
-    ../base/btop.nix
-    ../base/core.nix
-    ../base/i18n.nix
-    ../../../hardening/kernel-hardening.nix
-    ../base/monitoring.nix
-    ../base/nix.nix
-    ../base/packages.nix
-    ../base/ssh.nix
-    ../base/user-group.nix
-
-    # This server imports base files individually instead of the whole
-    # modules/nixos/base group, so pull the shared firewall in explicitly.
-    ../base/networking/firewall.nix
-
-    ../../base
-  ];
-}

outputs/default.nix

@@ -80,7 +80,6 @@ let
   nixosSystems = {
     x86_64-linux = import ./x86_64-linux (args // { system = "x86_64-linux"; });
     aarch64-linux = import ./aarch64-linux (args // { system = "aarch64-linux"; });
-    # riscv64-linux = import ./riscv64-linux (args // {system = "riscv64-linux";});
   };
   darwinSystems = {
     aarch64-darwin = import ./aarch64-darwin (args // { system = "aarch64-darwin"; });