feat: add stakpak package (v0.3.86)

Stakpak is a DevOps AI agent that generates infrastructure code,
debugs Kubernetes, configures CI/CD, and automates deployments.

- Source: github.com/stakpak/agent v0.3.86
- Rust workspace (14 crates), default binary: stakpak
- Dependencies: openssl (transitive via native-tls), pkg-config
- License: Apache-2.0

packages/stakpak/default.nix

@@ -0,0 +1,5 @@
+{
+  pkgs,
+  ...
+}:
+pkgs.callPackage ./package.nix { }

packages/stakpak/package.nix

@@ -0,0 +1,41 @@
+{
+  lib,
+  rustPlatform,
+  fetchFromGitHub,
+  pkg-config,
+  openssl,
+}:
+
+rustPlatform.buildRustPackage rec {
+  pname = "stakpak";
+  version = "0.3.86";
+
+  src = fetchFromGitHub {
+    owner = "stakpak";
+    repo = "agent";
+    rev = "v${version}";
+    hash = "sha256-k8fOgwn1Sh3Yg62ROzfKJym8AGewpZ3/2e3tHNRL7/0=";
+  };
+
+  cargoHash = "sha256-aa1YjyShoSNv9sC18gIx/kuAbxrNAsCE+2if8Rm2uiw=";
+
+  nativeBuildInputs = [ pkg-config ];
+
+  buildInputs = [
+    openssl
+  ];
+
+  doCheck = false;
+
+  passthru.category = "AI Agents";
+
+  meta = with lib; {
+    description = "DevOps AI agent that generates infrastructure code, debugs Kubernetes, configures CI/CD, and automates deployments";
+    homepage = "https://stakpak.io";
+    changelog = "https://github.com/stakpak/agent/releases/tag/v${version}";
+    license = licenses.asl20;
+    sourceProvenance = with sourceTypes; [ fromSource ];
+    mainProgram = "stakpak";
+    platforms = platforms.all;
+  };
+}