refactor(asio): keep chriskohlhoff namespace, adopt PR #109 content

Move pkgs/a/asio.lua -> pkgs/c/chriskohlhoff.asio.lua with
namespace="chriskohlhoff" so consumers can use both:
  mcpp add chriskohlhoff.asio@1.38.1  (fully qualified)
  mcpp add asio@1.38.1                (short form)

Update asio-module test project index accordingly.

Author: wellwei

pkgs/a/asio.lua pkgs/c/chriskohlhoff.asio.luapkgs/a/asio.lua renamed to pkgs/c/chriskohlhoff.asio.lua

@@ -2,7 +2,7 @@
 -- (Form B inline descriptor, separate-compilation mode)。
 --
 -- 注意事项
---   * 使用 `mcpp add asio@1.38.1` 引入；消费者需显式写
+--   * 使用 `mcpp add chriskohlhoff.asio@1.38.1` 引入；消费者需显式写
 --     `import std; import asio;`，因为本包设置 import_std = false。
 --   * 本包只支持模块方式消费。同一 translation unit 不要混用
 --     `#include <asio.hpp>` 和 `import asio;`，避免 inline 定义与模块 BMI
@@ -37,7 +37,7 @@
 --     `asio/coroutine.hpp`、`asio/streambuf.hpp`。
 package = {
     spec        = "1",
-    namespace   = "",
+    namespace   = "chriskohlhoff",
     name        = "asio",
     description = "Standalone asio exposed as the C++23 module `asio` (separate compilation)",
     licenses    = {"BSL-1.0"},

tests/examples/asio-module/mcpp.toml

@@ -1,11 +1,11 @@
 # Asio C++23-module consumer test project: `import std; import asio;`.
-# The public package is the default-root module-only `asio@1.38.1` package.
+# The public package is `chriskohlhoff.asio@1.38.1` (module-only).
 [package]
 name = "asio-module-tests"
 version = "0.1.0"
 
 [indices]
-default = { path = "../../.." }
+chriskohlhoff = { path = "../../.." }
 
-[dependencies]
+[dependencies.chriskohlhoff]
 asio = "1.38.1"