refactor!: replace build.rs with compile-time macro build steps

BREAKING CHANGE: Replace the `build`/`builds` feature system with
compile-time macro-driven generation. `gen_program!()` now automatically
invokes `build_comp!()` and `build_pathf!()` when the `comp`/`pathf`
features are enabled, eliminating the need for `build.rs` and
`[build-dependencies]` blocks.

This removes the `build` feature, the `mingling::build` module, and all
related build-time API functions. Completion scripts are now written to
`{target_directory}/mingling/` instead of `target/release/`. The
`mingling_cli` uses `build_comp!("mling")` for its custom binary name.

1 files changed, 47 insertions, 0 deletions

diff --git a/mingling_macros/src/lib.rs b/mingling_macros/src/lib.rs
index d00773c..1aaedb1 100644
--- a/mingling_macros/src/lib.rs
+++ b/mingling_macros/src/lib.rs
@@ -20,6 +20,9 @@ mod derive;
 mod func;
 mod systems;
 
+#[cfg(any(feature = "comp", feature = "pathf"))]
+mod build;
+
 mod extensions;
 mod utils;
 
@@ -1653,6 +1656,50 @@ pub fn gen_program(input: TokenStream) -> TokenStream {
     func::gen_program::gen_program_impl(input)
 }
 
+/// Executes the completion-script build at compile time and expands to nothing.
+///
+/// **This macro is only available with the `comp` feature.**
+///
+/// The completion scripts are written to `{target_directory}/mingling/` (the
+/// target directory is resolved via `cargo metadata`).
+///
+/// `gen_program!()` calls this macro automatically when the `comp` feature is
+/// enabled. It can also be invoked manually to customize the binary name:
+///
+/// - `build_comp!()` — uses the current package name (`CARGO_PKG_NAME`).
+/// - `build_comp!("mybin")` — uses the given binary name.
+///
+/// ```rust,ignore
+/// mingling::macros::build_comp!();
+/// // or:
+/// mingling::macros::build_comp!("mybin");
+/// ```
+#[cfg(feature = "comp")]
+#[proc_macro]
+pub fn build_comp(input: TokenStream) -> TokenStream {
+    build::comp_build_impl(input)
+}
+
+/// Executes the pathf type-mapping build at compile time and expands to nothing.
+///
+/// **This macro is only available with the `pathf` feature.**
+///
+/// The mapping files are written to `{target_directory}/mingling/{CARGO_PKG_NAME}/`
+/// (the target directory is resolved via `cargo metadata`), and are consumed by
+/// `gen_program!()` so that types defined in submodules are resolved automatically.
+///
+/// `gen_program!()` calls this macro automatically when the `pathf` feature is
+/// enabled.
+///
+/// ```rust,ignore
+/// mingling::macros::build_pathf!();
+/// ```
+#[cfg(feature = "pathf")]
+#[proc_macro]
+pub fn build_pathf(input: TokenStream) -> TokenStream {
+    build::pathf_build_impl(input)
+}
+
 /// Internal macro used by `gen_program!` to generate the completion infrastructure for
 /// shell completion support.
 ///