feat: add mcpp.toml for mcpp build support

mcpp.toml

@@ -0,0 +1,27 @@
+[package]
+name        = "mcpplibs.xpkg"
+version     = "0.0.39"
+description = "C++23 reference implementation of the xpkg V1 spec — `import mcpplibs.xpkg;`"
+license     = "Apache-2.0"
+repo        = "https://github.com/openxlings/libxpkg"
+
+[targets.xpkg]
+kind = "lib"
+
+# Library-root convention picks `src/xpkg.cppm` automatically.
+# The package ships five separate modules under the `mcpplibs.xpkg.*`
+# namespace (loader, index, executor, lua_stdlib) — they sit alongside
+# the primary `mcpplibs.xpkg` and all roll into the single libxpkg.a.
+#
+# `src/xpkg-lua-stdlib.cppm` is generated from `src/lua-stdlib/**/*.lua`
+# at xmake build time (see `before_build` in xmake.lua); the current
+# generated copy is committed so mcpp builds work without invoking the
+# xmake codegen path. Regenerate via `xmake build mcpplibs-xpkg-lua-stdlib`
+# whenever the .lua sources change.
+
+[dependencies]
+"mcpplibs.capi.lua" = "0.0.3"
+
+# `mcpp test` discovers tests/**/*.cpp + tests/**/*.cppm automatically.
+[dev-dependencies]
+gtest = "1.15.2"