Add Nix package, NixOS module, and tests for bambuddy

- packages.bambuddy: FastAPI backend + prebuilt React frontend assembled
  into the app-root layout upstream expects, behind a single `bambuddy`
  launcher (uvicorn --loop asyncio, ffmpeg on PATH, XDG state defaults).
  Pins upstream maziggy/bambuddy v1.2.5.7.
- nixosModules.default: services.bambuddy with host/port/dataDir,
  openFirewall, environment + environmentFile, extraPackages,
  DynamicUser + StateDirectory, systemd hardening, and
  CAP_NET_BIND_SERVICE for the virtual-printer FTPS/RTSP ports.
- checks.bambuddy-import: backend import + admin CLI smoke test.
- checks.bambuddy-service: two-node NixOS VM test covering the health
  endpoint, UI/static assets/manifest, SQLite + logs in the
  StateDirectory, journal startup check, cross-node reachability with
  openFirewall, custom host/port/env node, and loopback-only binding.
- overlay, run app, devShell, README, .gitignore.

pkgs/bambuddy/default.nix

@@ -0,0 +1,204 @@
+{
+  lib,
+  stdenv,
+  fetchFromGitHub,
+  buildNpmPackage,
+  python3,
+  makeWrapper,
+  ffmpeg,
+}:
+let
+  pname = "bambuddy";
+  version = "1.2.5.7";
+
+  src = fetchFromGitHub {
+    owner = "maziggy";
+    repo = "bambuddy";
+    rev = "188df76f8a7342542c0876dac68990ea2a8c8313"; # v1.2.5.7
+    hash = "sha256-KmlAdFoSIMa6Wahd4XPBvaBtpVR/5LPNMyaimuDZVb0=";
+  };
+
+  # Runtime Python dependencies, mirroring upstream requirements.txt.
+  # All of these ship in nixpkgs. Optional heavy extras (opencv4,
+  # fast-simplification) are included for feature parity with the upstream
+  # Docker image, which installs requirements.txt in full; the affected
+  # features (plate detection, STL thumbnails) degrade gracefully if absent.
+  pythonDeps =
+    ps: with ps; [
+      # Web framework
+      fastapi
+      uvicorn
+      uvloop
+      httptools
+      websockets
+      python-dotenv
+
+      # Database
+      sqlalchemy
+      aiosqlite
+      asyncpg
+      greenlet
+
+      # Pydantic / settings
+      pydantic
+      pydantic-settings
+
+      # Bambu Lab printer communication (MQTT / FTP)
+      paho-mqtt
+      aioftp
+      pyftpdlib
+      cryptography
+      pyopenssl
+      asyncssh
+
+      # 3MF processing
+      defusedxml
+
+      # Excel export
+      openpyxl
+
+      # Utilities
+      python-multipart
+      aiofiles
+
+      # QR codes / PDF generation / PDF thumbnails
+      qrcode
+      reportlab
+      pypdfium2
+
+      # STL thumbnails
+      trimesh
+      matplotlib
+      fast-simplification
+      networkx
+      lxml
+
+      # System monitoring
+      psutil
+
+      # Authentication
+      pyjwt
+      passlib
+      bcrypt
+      ldap3
+      pyotp
+
+      # HTTP clients
+      idna
+      httpx
+      certifi
+      curl-cffi
+      urllib3
+      aiohttp
+
+      # Plate detection
+      opencv4
+      numpy
+      pillow
+    ];
+
+  pythonEnv = python3.withPackages pythonDeps;
+
+
+  # Prebuilt React frontend. `vite build` emits to `../static` (the app root,
+  # next to `backend/`), matching the upstream Dockerfile.
+  frontend = buildNpmPackage {
+    pname = "${pname}-web";
+    inherit version src;
+
+    sourceRoot = "${src.name}/frontend";
+    npmDepsHash = "sha256-S+WU4jgs2DPWHHfspeo5k8vPECK+5SidGa8kzI4K4lw=";
+
+    # The source tree arrives from the store read-only, but `vite build`
+    # empties and writes ../static (the repo ships a committed static/ dir).
+    preBuild = ''
+      chmod -R u+w "$NIX_BUILD_TOP/${src.name}"
+      rm -rf ../static
+    '';
+
+    installPhase = ''
+      runHook preInstall
+      mkdir -p $out/share
+      cp -r ../static $out/share/static
+      runHook postInstall
+    '';
+
+    meta = {
+      description = "Web frontend for Bambuddy";
+      license = lib.licenses.agpl3Only;
+      platforms = lib.platforms.unix;
+    };
+  };
+in
+stdenv.mkDerivation {
+  inherit pname version src;
+
+  dontBuild = true;
+
+  nativeBuildInputs = [ makeWrapper ];
+
+  buildInputs = [ pythonEnv ];
+
+  passthru = {
+    inherit pythonEnv frontend;
+  };
+
+  installPhase = ''
+    runHook preInstall
+
+    # App root: `backend/` (Python sources) + `static/` (prebuilt frontend).
+    # backend.app.core.config resolves both relative to this root, exactly
+    # like the upstream Docker image (/app/backend + /app/static).
+    mkdir -p $out/share/bambuddy
+    cp -r ${src}/backend $out/share/bambuddy/backend
+    cp -r ${frontend}/share/static $out/share/bambuddy/static
+    chmod -R u+w $out/share/bambuddy
+
+    # The upstream test suite is not shipped in the runtime package.
+    rm -rf $out/share/bambuddy/backend/tests
+    find $out/share/bambuddy -type d -name __pycache__ -prune -exec rm -rf {} +
+
+    install -Dm644 ${src}/LICENSE -t $out/share/licenses/bambuddy
+
+    mkdir -p $out/bin
+    install -Dm755 ${./wrapper.sh} $out/bin/bambuddy
+    # Substitute at build time so @out@ resolves to THIS package's path.
+    # (A separate replaceVars derivation would substitute its own outPath
+    # instead — which silently broke the PYTHONPATH in the launcher.)
+    substituteInPlace $out/bin/bambuddy \
+      --replace-warn '@out@' "$out" \
+      --replace-warn '@pythonEnv@' "${pythonEnv}"
+    # ffmpeg is used for timelapse conversion and camera stream re-encoding.
+    wrapProgram $out/bin/bambuddy \
+      --prefix PATH : ${lib.makeBinPath [ ffmpeg ]}
+
+    runHook postInstall
+  '';
+
+  # Fix up the interpreter reference in the substituted wrapper.
+  preFixup = ''
+    patchShebangs $out/bin/bambuddy
+  '';
+
+  meta = {
+    description = "Self-hosted command center for Bambu Lab 3D printers";
+    longDescription = ''
+      Bambuddy is a self-hosted command center for Bambu Lab 3D printers —
+      from a single A1 to an entire print farm. Monitor printers in real
+      time, archive every print automatically, slice and queue jobs locally,
+      and manage the whole workflow without Bambu's cloud.
+
+      This package bundles the FastAPI backend and the prebuilt React
+      frontend behind a single `bambuddy` launcher. Configuration is done via
+      environment variables (DATA_DIR, LOG_DIR, HOST, PORT, ...) — see the
+      NixOS module (`services.bambuddy`) or upstream `.env.example` for the
+      full list.
+    '';
+    homepage = "https://bambuddy.cool/";
+    changelog = "https://github.com/maziggy/bambuddy/releases/tag/v${version}";
+    license = lib.licenses.agpl3Only;
+    sourceProvenance = with lib.sourceTypes; [ fromSource ];
+    platforms = lib.platforms.unix;
+    mainProgram = "bambuddy";
+  };
+}