- Add `#[must_use]` to public constructors and getters
- Change `init_with_config` to accept `&PathfinderConfig` instead of
  owned value
- Refactor `map_or_else` and `or_insert_with` for clippy compliance
- Add `#![deny(clippy::pedantic)]` and `#![deny(clippy::nursery)]`
- Document error cases in public API docs
- Simplify duplicated dispatcher_clap analysis logic

Remove the BasicStructPattern from pathf's pattern analyzer to eliminate
noise from plain structs not associated with any Mingling macro.

Also clean up the now-unused `basic_struct` module and update the
integration test to assert plain structs are no longer collected.

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.

Add a new `#[command]` attribute macro (feature-gated behind
`extra_macros`) that converts a plain function with a `Vec<String>`
parameter into a fully wired Mingling command. The macro generates a
`dispatcher!` call, a `#[chain]` wrapper, and a hidden module
re-exporting
all generated types.

Also add `CommandPattern` to the pathf pattern analyzer to recognize
`#[command]`-annotated functions and track their generated hidden
modules.

Add `AnalyzeItem::foreign()` and `AnalyzeItem::local()` constructors to
distinguish items resolved via `use` imports from local definitions.
Update `GroupPattern` to collect use imports at file and module levels,
resolving `group!(TypeName)` against them.  Migrate all pattern
implementations to use the new constructors, and adjust
`type_mapping_builder` to skip the file's own module prefix for foreign
items.

Add `#![deny(missing_docs)]` across multiple crates and fill in
documentation for all public items, including struct fields, enum
variants, trait methods, and proc macros.  Also mark two shell scripts
as executable.