feat: add entry metadata system with compile-time typed values

Add `Metadata<B>` trait and `#[metadata(Entry)]` attribute macro
to attach arbitrary, compile-time-typed metadata to entries.
Implement `ProgramCollect::get_metadata<T>()` for runtime retrieval,
backed by a global registry populated by `register_metadata!`.

Extend `pathf` with `MetadataPattern` to resolve metadata types
across modules at build time. Add two examples demonstrating
metadata usage with and without pathf integration.

1 files changed, 2 insertions, 0 deletions

diff --git a/mingling_pathf/src/patterns.rs b/mingling_pathf/src/patterns.rs
index 964fe7c..fcc50c3 100644
--- a/mingling_pathf/src/patterns.rs
+++ b/mingling_pathf/src/patterns.rs
@@ -9,6 +9,7 @@ pub use dispatcher_clap::*;
 pub use group::*;
 pub use grouped_derive::*;
 pub use help::*;
+pub use metadata::*;
 pub use pack::*;
 pub use renderer::*;
 
@@ -21,5 +22,6 @@ mod dispatcher_clap;
 mod group;
 mod grouped_derive;
 mod help;
+mod metadata;
 mod pack;
 mod renderer;