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.

3 files changed, 6 insertions, 5 deletions

diff --git a/docs/pages/concepts/2-resource.md b/docs/pages/concepts/2-resource.md
index ad7ee16..6f0ef99 100644
--- a/docs/pages/concepts/2-resource.md
+++ b/docs/pages/concepts/2-resource.md
@@ -34,7 +34,8 @@ For example:
 
 ```rust
 @@@ use mingling::res::ResExitCode;
-@@@ pack!(ErrorFileNotFound = ());
+@@@ #[derive(Grouped, Wrap)]
+@@@ pub struct ErrorFileNotFound(());
 #[chain]
 fn handle_error_file_not_found(
     error: ErrorFileNotFound,
diff --git a/docs/pages/concepts/3-any-output.md b/docs/pages/concepts/3-any-output.md
index f02805f..2b07906 100644
--- a/docs/pages/concepts/3-any-output.md
+++ b/docs/pages/concepts/3-any-output.md
@@ -20,7 +20,7 @@ AnyOutput<G>
  
 Here `G` is the program enum generated by `gen_program!()` (i.e., `ThisProgram` as you know it).
 
-Each type annotated with `pack!` or `#[derive(Grouped)]` is assigned to one variant of this enum.
+Each type annotated with `#[derive(Grouped)]` (or `#[derive(Grouped, Wrap)]`) is assigned to one variant of this enum.
 
 ## ChainProcess: Data + Routing
 
@@ -48,7 +48,7 @@ trait Grouped<G> {
 }
 ```
  
-When you use `pack!(ResultName = String)`, the macro automatically implements `Grouped` for `ResultName`, and `member_id()` returns the corresponding enum variant. The dispatcher looks at `member_id` and finds the matching Chain or Renderer.
+When you write `#[derive(Grouped)]` on `ResultName`, the derive automatically implements `Grouped` for `ResultName`, and `member_id()` returns the corresponding enum variant. The dispatcher looks at `member_id` and finds the matching Chain or Renderer.
 
 `to_chain()` and `to_render()` are essentially convenience methods on `AnyOutput` that construct `ChainProcess::Ok(any, Chain)` and `ChainProcess::Ok(any, Renderer)` respectively.
 
@@ -66,7 +66,7 @@ This mechanism ensures **type safety**: the dispatch code generated by `gen_prog
 > [!TIP]
 > In day-to-day dev, you don't need to manually touch `AnyOutput` or `ChainProcess`.
 >
-> Macros like `pack!`, `#[chain]`, and `#[renderer]` handle all the wrapping and unwrapping for you.
+> Macros and derives like `#[derive(Grouped, Wrap)]`, `#[chain]`, and `#[renderer]` handle all the wrapping and unwrapping for you.
 
 <p align="center" style="font-size: 0.85em; color: gray;">
     Written by @Weicao-CatilGrass
diff --git a/docs/pages/concepts/4-program-collect.md b/docs/pages/concepts/4-program-collect.md
index c5203c3..bc1fbc9 100644
--- a/docs/pages/concepts/4-program-collect.md
+++ b/docs/pages/concepts/4-program-collect.md
@@ -9,7 +9,7 @@ Every Mingling program ends with a `gen_program!()` call. Behind the scenes, it
 
 ### 1. Generate an enum
 
-Scans the current module for all types marked with `pack!`, `#[chain]`, `#[renderer]` and similar macros, then generates an enum variant for each type.
+Scans the current module for all types marked with `#[derive(Grouped)]`, `#[chain]`, `#[renderer]` and similar macros, then generates an enum variant for each type.
 
 This enum is the type of `G` in `AnyOutput<G>` — the scheduler uses enum variants to distinguish different data flowing through the pipeline.