How to make a Rust dropped item despawn time plugin (global multiplier and per-item overrides)

using UnityEngine;
using System;
using System.Collections.Generic;
using Newtonsoft.Json;
using Oxide.Core;

namespace Oxide.Plugins
{
    [Info("Item Despawn Time", "RustPluginGenerator", "1.0.0")]
    [Description("Scales how long dropped items stay in the world using a global multiplier and per-item overrides.")]
    public class ItemDespawnTime : RustPlugin
    {
        private const string PermAdmin = "itemdespawntime.admin";

        private PluginConfig config;

        private class PluginConfig
        {
            [JsonProperty("Global multiplier")]
            public float GlobalMultiplier { get; set; } = 1f;

            [JsonProperty("Per-item overrides (shortname: seconds)")]
            public Dictionary<string, float> Overrides { get; set; } = new Dictionary<string, float>(StringComparer.OrdinalIgnoreCase)
            {
                ["loot-bag"] = 600f,
                ["scrap"] = 300f
            };

            [JsonProperty("Debug logging")]
            public bool Debug { get; set; } = false;
        }

        protected override void LoadDefaultConfig() => config = new PluginConfig();

        protected override void LoadConfig()
        {
            base.LoadConfig();
            try
            {
                config = Config.ReadObject<PluginConfig>();
                if (config == null) throw new Exception();
            }
            catch
            {
                PrintWarning("Configuration file is invalid, using defaults");
                LoadDefaultConfig();
            }
            SaveConfig();
        }

        protected override void SaveConfig() => Config.WriteObject(config);

        private void Init()
        {
            permission.RegisterPermission(PermAdmin, this);
        }

        private void OnItemDropped(Item item, BaseEntity entity)
        {
            if (item == null || entity == null || entity.IsDestroyed) return;
            if (config == null) return;

            BaseEntity target = entity as DroppedItemContainer;
            if (target == null) target = entity as DroppedItem;
            if (target == null) return;

            string shortname = item.info != null ? item.info.shortname : target.ShortPrefabName;
            if (string.IsNullOrEmpty(shortname)) return;

            float newDuration;

            if (config.Overrides != null && config.Overrides.TryGetValue(shortname, out float overrideSeconds))
            {
                if (overrideSeconds <= 0f) return;
                newDuration = overrideSeconds;
            }
            else
            {
                // Default dropped item lifetime in Rust is 5 minutes (300 seconds).
                const float defaultLifetime = 300f;
                newDuration = defaultLifetime * config.GlobalMultiplier;
                if (newDuration <= 0f) return;
            }

            // BaseEntity no longer exposes despawnTime/spawnTime; schedule our own despawn timer instead.
            NextTick(() =>
            {
                if (target == null || target.IsDestroyed) return;
                timer.Once(newDuration, () =>
                {
                    if (target == null || target.IsDestroyed) return;
                    target.Kill();
                });
            });

            if (config.Debug)
            {
                Puts(string.Format("Scheduled despawn for {0} in {1:0}s", shortname, newDuration));
            }
        }

        [ConsoleCommand("itemdespawn.status")]
        private void CmdStatus(ConsoleSystem.Arg arg)
        {
            if (arg == null) return;

            var player = arg.Player();
            if (player != null && !permission.UserHasPermission(player.UserIDString, PermAdmin))
            {
                arg.ReplyWith("You do not have permission to use this command.");
                return;
            }

            int overrideCount = config?.Overrides?.Count ?? 0;
            string reply = string.Format("Multiplier: {0:0.##} | Overrides: {1} | Debug: {2}",
                config?.GlobalMultiplier ?? 1f, overrideCount, config != null && config.Debug);
            arg.ReplyWith(reply);
        }
    }
}