Unreal Engine Linux server for NetCraftGames

You are preparing an existing multiplayer game so a hosting service (NetCraftGames) can run its dedicated server on a Linux machine.
Rules for you:
- Make ONLY the changes listed below. Do not redesign game logic. Do not add multiplayer to a game that has none. If something below cannot be done without a redesign, stop and tell me instead of improvising.
- Never put a password, key or token in code or in any file. Read secrets from environment variables.
- Run every proof step at the end and show me the real output. If a proof step fails, fix it or tell me exactly why you cannot.
- If a step needs a tool you do not have, say so and stop at that step. Do not invent a substitute and do not pretend the step passed.

Facts about the host (exact):
- Linux x86-64, glibc 2.39 or older for every compiled program in the upload.
- The server starts as an unprivileged user in /game. Writable places: /game/saves and a 256 MB /tmp. Nothing is installed, downloaded or compiled on the host. The start command is a fixed list of arguments, not a shell string.
- The host (Ubuntu 24.04 LTS) provides these programs: sh, bash, dash, python3, node, node24 (Python 3.12, Node.js 24.21.0). There is no Java, .NET, Deno or Bun on the host unless you ship it inside the upload.
- Nothing is installed or downloaded on the host: packages travel inside the upload, built for Linux x64 on the owner's own computer.
- A game server cannot look up other websites by name (DNS is closed to it on purpose), so do not make the server depend on calling an outside address by name.
- The host does not set a PORT variable. The port your server uses by default must be the port written in the manifest.
- The host stops the server with SIGTERM and waits up to the number of seconds in the manifest (between 1 and 300).
- The upload is one .tar.gz of at most 512 MiB with at most 10,000 files, no symlinks and no setuid files.
- The host checks your server from outside with a 3 second timeout per request.

TASK: Package this Unreal Engine project's Linux dedicated server. Do not change replication or gameplay. If a step is already done, skip it and say so.
1. Make sure a Server target exists (YourGameServer.Target.cs). Package for Linux, server only: RunUAT BuildCookRun -project="YourGame.uproject" -platform=Linux -server -noclient -serverconfig=Shipping -cook -build -stage -pak -archive.
2. Start it with: ./YourGameServer.sh /Game/Maps/YourStartMap -port=7777 -log  and confirm it stays running with no display.
3. Add a small side HTTP listener on TCP 8080 (Unreal's HTTP server module, or a tiny socket server in a game instance subsystem) for R2 and R3, and a loopback listener for R4 that reports the number of connected player controllers.
4. Shutdown (R5): verify with a real kill -TERM that the server exits cleanly and writes its save under /game/saves. If SIGTERM does not do that on this Unreal version, tell me and propose a safe alternative instead of guessing.

Server requirements (all exact):
R1  Listen on 0.0.0.0 (never 127.0.0.1 only, never a random port). The game port comes from the -port argument (or the PORT environment variable) and defaults to 7777.
R2  Health probe: a small side HTTP listener on TCP port 8080. GET /health answers HTTP 200 with the body exactly "ok" within 3 seconds. It must not touch game state. Return 503 if the server loop is stalled or shutting down.
R3  Join probe: GET /join-probe on the same side listener answers 200 with a body that contains "joinable" while a new player could be admitted, otherwise 503 with the body "full" or "stopping". It needs no login and exposes nothing private.
R4  Player count: a second HTTP listener bound to 127.0.0.1 only, port 9090. GET /players answers 200 with JSON {"players": N}, where N is the number of connected players, a whole number from 0 to 10,000, in a body under 4 KB. Do not count a health probe, a join probe or a player who is only in a reconnect grace window.
R5  Shutdown: on SIGTERM (and SIGINT) stop admitting players, tell connected clients, write the save atomically (write a temporary file in the same folder, flush it, then rename it) under /game/saves, close sockets and exit with code 0 within the grace seconds.
R6  Saves and every other file the server writes live under /game/saves only. Read the folder from an environment variable SAVE_DIR and default to /game/saves (use ./saves when running on your own computer).
R7  Log events (join, leave, error), not every tick. The host drops log lines above its rate limit.
Run the listeners on a background thread or task. Read the player count and the "accepting players" flag from values the main game loop updates.

5. Write ncg.json (profile "large" is recommended for Unreal servers), replacing the program and map names with your real ones:

----- ncg.json (start) -----
{
  "ncg": 1,
  "game": {
    "name": "My Game"
  },
  "version": "0.1.0",
  "build": {
    "dir": "./Saved/StagedBuilds/LinuxServer"
  },
  "manifest": {
    "engine": "unreal-replication",
    "transport": "udp",
    "platforms": [
      "windows"
    ],
    "mode": "dedicated",
    "networkingImplemented": true,
    "os": "linux",
    "arch": "x64",
    "command": [
      "/game/YourGameServer.sh",
      "/Game/Maps/YourStartMap",
      "-port=7777"
    ],
    "ports": [
      {
        "port": 7777,
        "protocol": "udp"
      },
      {
        "port": 8080,
        "protocol": "tcp"
      }
    ],
    "profile": "large",
    "savePath": "/game/saves",
    "health": {
      "type": "http",
      "port": 8080,
      "path": "/health",
      "expected": "ok"
    },
    "playerProbe": {
      "type": "http",
      "port": 9090,
      "path": "/players"
    },
    "joinProbe": {
      "type": "http",
      "port": 8080,
      "path": "/join-probe",
      "expected": "joinable"
    },
    "shutdown": {
      "signal": "SIGTERM",
      "graceSeconds": 60
    },
    "idleSupported": true
  }
}
----- ncg.json (end) -----

About ncg.json (the project file the ncg tool reads; it is never packed into the upload):
- Write it in the project root with exactly the content shown. Change only: "game.name" (the real name of the game, 1 to 100 characters), "build.dir" (the folder that holds the final Linux server files), "manifest.platforms" (the platforms the game's players really use) and, where a step says so, the program name in "manifest.command".
- Everything inside the build folder becomes /game on the host, so "/game/server" means the file "server" at the top of that folder.
- "ncg pack <folder>" only zips a folder into the upload and checks it. It does not build, bundle or install anything, so every step above that builds something is yours.

Proof (run these and show me the real output):
P1  Start the finished Linux server the way the host will: the exact command from ncg.json, in a Linux shell (WSL or an ubuntu:24.04 container if you are on Windows or Mac), with no environment variables set except PATH, LANG and HOME.
P2  curl -s -w " %{http_code}" http://127.0.0.1:8080/health  must print ok and 200.
P3  curl -s http://127.0.0.1:9090/players  must print {"players":0}. Connect one real client: it must become {"players":1}.
P4  Send SIGTERM (kill -TERM <pid>). The process must exit with code 0 inside the grace seconds and the save file must exist and parse.
P5  If the ncg tool is installed, run "ncg check" in the project folder and fix everything it lists. If it is not installed, say so; do not write a substitute.