feat(picker): add core trait, types, and builder macro for argument

parsing

Implement the foundational `mingling_picker` library along with its
companion
`mingling_picker_macros` crate. The picker provides:

- `Pickable` trait for parsing types from raw strings
- `PickerResult` enum modeling parse outcomes
- `Picker` struct for storing and indexing command-line arguments
- `PickerRequirement` struct for declarative parameter definitions
- `PickerPattern` family (1..32) of typed pattern structs via the
  `internal_repeat` proc macro
- `req!` proc macro as a succinct builder for `PickerRequirement`

Re-export `mingling_picker::macros::*` from the `mingling` crate when
the
`picker` feature is enabled, replacing the previous wildcard re-export
of
`mingling_macros`.

1 files changed, 12 insertions, 0 deletions

diff --git a/mingling_picker/src/picker/patterns.rs b/mingling_picker/src/picker/patterns.rs
new file mode 100644
index 0000000..74a8cd8
--- /dev/null
+++ b/mingling_picker/src/picker/patterns.rs
@@ -0,0 +1,12 @@
+use crate::{Pickable, PickerArguments, PickerRequirement};
+
+mingling_picker_macros::internal_repeat! (1..=32 => {
+    pub struct PickerPattern$<'a, (Type$,)+>
+    where (Type$: Pickable + Default,)+
+    {
+        pub args: PickerArguments<'a>,
+        (
+            pub require_$: PickerRequirement<'a, Type$>,
+        )+
+    }
+});