chore: 删除多个客户端模块

移除以下未完成的客户端模块：
- C++ 客户端和 demo
- .NET 客户端和 demo
- Kotlin 客户端和 demo
- Lua 客户端和 demo
- PHP 客户端和 demo
- Ruby 客户端和 demo
- Rust 客户端和 demo

更新根目录 README.md，移除相关说明。

kenaito-conf-dotnet-client-demo/KenaitoConfDemo.csproj

@@ -1,9 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
-  </PropertyGroup>
-  <ItemGroup>
-    <ProjectReference Include="..\kenaito-conf-dotnet-client\KenaitoConf.csproj" />
-  </ItemGroup>
-</Project>

kenaito-conf-dotnet-client-demo/Program.cs

@@ -1,65 +0,0 @@
-using System;
-using System.Collections.Generic;
-using KenaitoConf;
-
-var configValues = new Dictionary<string, string>
-{
-    { "database.host", Environment.GetEnvironmentVariable("DATABASE_HOST") ?? "192.168.1.1" },
-    { "database.port", Environment.GetEnvironmentVariable("DATABASE_PORT") ?? "8888" },
-    { "database.name", Environment.GetEnvironmentVariable("DATABASE_NAME") ?? "xxxx" },
-    { "database.user", Environment.GetEnvironmentVariable("DATABASE_USER") ?? "xxxx" },
-    { "database.password", Environment.GetEnvironmentVariable("DATABASE_PASSWORD") ?? "xxxxxxxx" },
-};
-
-var config = new Config
-{
-    BaseUrl = Environment.GetEnvironmentVariable("KENAITO_BASE_URL") ?? "http://localhost:8080",
-    AppName = Environment.GetEnvironmentVariable("KENAITO_APP_NAME") ?? "kenaito-springboot-demo",
-    Env = Environment.GetEnvironmentVariable("KENAITO_PROFILE") ?? "daily",
-    Version = Environment.GetEnvironmentVariable("KENAITO_VERSION") ?? "latest",
-    Token = Environment.GetEnvironmentVariable("KENAITO_TOKEN") ?? "",
-    SyncInterval = int.Parse(Environment.GetEnvironmentVariable("KENAITO_SYNC_INTERVAL") ?? "10"),
-    CacheDir = Environment.GetEnvironmentVariable("KENAITO_CACHE_DIR") ?? ".",
-};
-
-var client = new ConfigClient(config);
-
-client.OnChange(changed =>
-{
-    foreach (var kv in changed)
-    {
-        if (configValues.ContainsKey(kv.Key))
-        {
-            configValues[kv.Key] = kv.Value;
-            Console.Error.WriteLine($"config updated: {kv.Key} = {kv.Value}");
-        }
-    }
-});
-
-try
-{
-    await client.StartAsync();
-    var remote = client.GetAll();
-    foreach (var key in new List<string>(configValues.Keys))
-    {
-        if (remote.ContainsKey(key))
-            configValues[key] = remote[key];
-    }
-    Console.Error.WriteLine($"loaded {remote.Count} configs from remote");
-}
-catch (Exception e)
-{
-    Console.Error.WriteLine($"failed to init config client: {e.Message}");
-}
-
-Console.WriteLine("Current configs:");
-foreach (var kv in configValues)
-    Console.WriteLine($"  {kv.Key} = {kv.Value}");
-
-Console.WriteLine("\nListening for config changes... (press Ctrl+C to stop)");
-var cts = new System.Threading.CancellationTokenSource();
-Console.CancelKeyPress += (_, e) => { e.Cancel = true; cts.Cancel(); };
-try { await System.Threading.Tasks.Task.Delay(System.Threading.Timeout.Infinite, cts.Token); }
-catch (System.Threading.Tasks.TaskCanceledException) { }
-client.Stop();
-Console.WriteLine("Shutting down...");