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-lua-client-demo/app.lua

@@ -1,49 +0,0 @@
-local ConfigClient = require("kenaito-conf")
-
-local config_values = {
-    ["database.host"] = os.getenv("DATABASE_HOST") or "192.168.1.1",
-    ["database.port"] = os.getenv("DATABASE_PORT") or "8888",
-    ["database.name"] = os.getenv("DATABASE_NAME") or "xxxx",
-    ["database.user"] = os.getenv("DATABASE_USER") or "xxxx",
-    ["database.password"] = os.getenv("DATABASE_PASSWORD") or "xxxxxxxx",
-}
-
-local config = {
-    baseUrl = os.getenv("KENAITO_BASE_URL") or "http://localhost:8080",
-    appName = os.getenv("KENAITO_APP_NAME") or "kenaito-springboot-demo",
-    env = os.getenv("KENAITO_PROFILE") or "daily",
-    version = os.getenv("KENAITO_VERSION") or "latest",
-    token = os.getenv("KENAITO_TOKEN") or "",
-    syncInterval = tonumber(os.getenv("KENAITO_SYNC_INTERVAL") or "10"),
-    cacheDir = os.getenv("KENAITO_CACHE_DIR") or ".",
-}
-
-local client = ConfigClient.new(config)
-
-client:on_change(function(changed)
-    for k, v in pairs(changed) do
-        if config_values[k] then
-            config_values[k] = v
-            print("config updated: " .. k .. " = " .. v)
-        end
-    end
-end)
-
-client:start()
-
-local remote = client:get_all()
-for k, v in pairs(remote) do
-    if config_values[k] then
-        config_values[k] = v
-    end
-end
-
-print("Current configs:")
-for k, v in pairs(config_values) do
-    print("  " .. k .. " = " .. v)
-end
-
-print("\nListening for config changes... (press Ctrl+C to stop)")
-while true do
-    os.execute("sleep 1")
-end