feat(halo): add different llama servers

systems/x86_64-linux/halo/llama-server-coder-next.nix

@@ -0,0 +1,57 @@
+{
+  pkgs,
+  lib,
+  ...
+}:
+{
+  systemd.services.llama-server = {
+    description = "llama.cpp server (Qwen3-Coder-Next, ROCm)";
+    after = [ "network-online.target" ];
+    wants = [ "network-online.target" ];
+    wantedBy = [ "multi-user.target" ];
+
+    environment = {
+      HOME = "%S/llama-server";
+      HF_HOME = "%S/llama-server";
+    };
+
+    serviceConfig = {
+      Type = "simple";
+      DynamicUser = true;
+      SupplementaryGroups = [
+        "video"
+        "render"
+      ];
+      StateDirectory = "llama-server";
+      CacheDirectory = "llama-server";
+      WorkingDirectory = "%S/llama-server";
+      ExecStartPre = "${pkgs.coreutils}/bin/mkdir -p %C/llama-server/kv-slots-coder-next";
+      ExecStart = lib.concatStringsSep " " [
+        "${pkgs.llama-cpp-rocm}/bin/llama-server"
+	"--flash-attn on"
+        "--parallel 1"
+        "--jinja"
+        "--host 0.0.0.0"
+        "--port 8000"
+        "--no-mmap"
+        "--n-gpu-layers 99"
+        "--threads 8"
+        "--ubatch-size 256"
+        "-ctk bf16 -ctv bf16"
+        "--fit on"
+        "--no-context-shift"
+        "-hf unsloth/Qwen3-Coder-Next-GGUF:UD-Q8_K_XL"
+        "--alias qwen3-coder-next"
+        "--temp 1.0 --top-p 0.95 --min-p 0.01 --top-k 40"
+        "--slot-save-path %C/llama-server/kv-slots-coder-next"
+      ];
+      Restart = "on-failure";
+      RestartSec = 10;
+
+      PrivateTmp = true;
+      ProtectSystem = "strict";
+      ProtectHome = true;
+      NoNewPrivileges = true;
+    };
+  };
+}