refactor!: replace pack! macros with derive-based pipeline types

Remove the `pack!`, `pack_err!`, `pack_structural!`, and
`pack_err_structural!` macros, replacing all pipeline type definitions
with `#[derive(Grouped)]` and `#[derive(Grouped, Wrap)]` attributes.
This changes the generated struct shape from named-field structs with an
`inner` field to tuple structs accessed via `.0`, and removes the
auto-generated `name` and `info` fields from error types.

1 files changed, 8 insertions, 4 deletions

diff --git a/examples/example-combine-pathf-metadata/src/sub/mod.rs b/examples/example-combine-pathf-metadata/src/sub/mod.rs
index ba56285..38efa2f 100644
--- a/examples/example-combine-pathf-metadata/src/sub/mod.rs
+++ b/examples/example-combine-pathf-metadata/src/sub/mod.rs
@@ -7,6 +7,7 @@ use std::io::Write;
 
 // Implicit dispatcher form — creates `CMDHello` / `EntryHello` in this module
 dispatcher!("hello");
+
 // Creates `CMDDescription` / `EntryDescription` in this module
 dispatcher!("desc", EntryDescription);
 
@@ -27,14 +28,17 @@ pub fn hello_desc() -> Description {
     }
 }
 
-pack!(ResultName = String);
-pack!(DescResult = String);
+#[derive(Grouped, Wrap)]
+pub struct ResultName(String);
+
+#[derive(Grouped, Wrap)]
+pub struct DescResult(String);
 
 /// Chain for `hello` — reads the name and produces a `ResultName`.
 #[chain]
 pub fn handle_hello(args: EntryHello) -> Next {
     let name: ResultName = args
-        .inner
+        .0
         .first()
         .cloned()
         .unwrap_or_else(|| "World".to_string())
@@ -51,7 +55,7 @@ pub fn handle_desc(_args: EntryDescription) -> Next {
         None => "EntryHello has no description".to_string(),
     };
     // --------- IMPORTANT ---------
-    DescResult::new(msg).to_render()
+    DescResult(msg).to_render()
 }
 
 /// Renders the greeting message with the provided name.