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, 40 insertions, 0 deletions

diff --git a/mingling_pathf/test/src/test_files/test_metadata.rs b/mingling_pathf/test/src/test_files/test_metadata.rs
new file mode 100644
index 0000000..52a2d4c
--- /dev/null
+++ b/mingling_pathf/test/src/test_files/test_metadata.rs
@@ -0,0 +1,40 @@
+// Root-level metadata functions
+#[mingling::macros::metadata(EntryGreet1)]
+pub fn get_desc1() -> Description1 {
+    Description1 {}
+}
+
+#[metadata(EntryGreet2)]
+fn get_desc2() -> Description2 {
+    Description2 {}
+}
+
+// Local DataType (defined in-crate) + foreign DataType
+#[metadata(EntryGreet3)]
+pub fn get_desc3() -> LocalType3 {
+    LocalType3 {}
+}
+
+use std::collections::HashMap;
+
+#[metadata(EntryGreet4)]
+fn get_desc4() -> HashMap<String, String> {
+    HashMap::new()
+}
+
+#[metadata(EntryGreet5)]
+pub fn get_desc5() -> crate::fully::Qualified5 {
+    crate::fully::Qualified5 {}
+}
+
+pub mod sub {
+    #[mingling::macros::metadata(EntrySub1)]
+    pub fn get_sub1() -> SubType1 {
+        SubType1 {}
+    }
+
+    #[metadata(EntrySub2)]
+    fn get_sub2() -> SubType2 {
+        SubType2 {}
+    }
+}