Replace intra-doc links with explicit URLs for types that are
not accessible from the current module scope, and add missing
panic documentation section.

Add `#[allow(clippy::future_not_send)]` to chain invocation methods and
clarify Send requirements for `exec` bounds.

Refactor `GlobalResources` from a type-erased `Arc<Mutex<HashMap<...>>>`
alias into a `GlobalResContainer` struct with per-resource mutexes.
This prevents nested `modify_res` calls from deadlocking, allows
independent containers to coexist, and keeps `Program`'s public
resource API unchanged.

Replace bool-based settings with enums, refine visibility and
signatures, and standardize `Self` usage across the crate.

- Introduce `ErrorOutput`, `RenderOutput`, `PanicSilence`, `Verbosity`,
  `ColorOutput`, and `ProgressOutput` enums for clearer configuration
  semantics
- Make `GlobalResources`, `ProgramCell`, and
  `split_input`/`split_input_string` public
- Change hook info parameters to accept references and
  `split_input_string` to take `&str`
- Apply `Self` shorthand throughout implementations and add
  `#[must_use]` attributes where appropriate
- Enable strict clippy lints with targeted allowances

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.

clause