Add a new `test-all` command that runs tests across all crates with
optional per-crate command overrides via `mingling-ci.toml` files.

When a program declares no chains, the synthesized `do_chain` now
respects the `async` feature by emitting a boxed future signature
with a `Box::pin(async { panic! })` body, matching the trait
requirement and fixing E0053 in async builds.

BREAKING CHANGE: Replace the `build`/`builds` feature system with
compile-time macro-driven generation. `gen_program!()` now automatically
invokes `build_comp!()` and `build_pathf!()` when the `comp`/`pathf`
features are enabled, eliminating the need for `build.rs` and
`[build-dependencies]` blocks.

This removes the `build` feature, the `mingling::build` module, and all
related build-time API functions. Completion scripts are now written to
`{target_directory}/mingling/` instead of `target/release/`. The
`mingling_cli` uses `build_comp!("mling")` for its custom binary name.

BREAKING CHANGE: `#[completion]` functions must now take `ShellContext`
by value instead of `&ShellContext`. Reference parameters are reserved
for resource injection.

Allow completion functions to omit the context parameter, accept owned
ShellContext or any From<&ShellContext> type, and return any type
implementing Into<Suggest>. Add From<&str> for SuggestItem and derive
Clone for ShellContext.

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.

Add `#[derive(Wrap)]` to treat a struct as its inner type, generating
`From`, `Deref`, and `DerefMut` implementations. Supports single-field
structs or multi-field structs with a `#[wrap]`-marked field.

The `dispatcher!` macro no longer requires a `CMD*` dispatcher type
argument; the dispatcher struct is now generated internally as
`__Dispatcher{Pascal}`. The `Node` type, `node!` macro, and
`Dispatcher::node()` / `clone_dispatcher()` methods are removed.

Dispatchers are now always registered at compile time, removing the
`with_dispatcher` / `with_dispatchers` methods and the
`PathfinderConfig` API. The `dispatch_tree` feature now only controls
the matching strategy (trie vs linear list).