docs(core): surface the fluent combinators in the API reference via the guide

[btravers]

Why

Someone looking for flatMap (or any combinator) in the generated API reference found nothing. Result / AsyncResult are discriminated-union aliases, and TypeDoc can't list a method surface on a union alias — so the combinators (map, flatMap, bind, match, unwrap, …) rendered nowhere.

Approach

The fix is not to expose a standalone method type. Doing so would split and double the surface — a near-identical ResultMethods and AsyncResultMethods block, each a hop away from the type you actually landed on — when the mental model (and the guide) is that there's one shared method surface. Instead:

• Link to the guide. The Result / AsyncResult type docs now point at the intent-organized Choosing a combinator guide, which already documents both in one table. ResultMethods stays @internal.
• Reorder the reference. The core typedoc.json sets an explicit categoryOrder (Facade → Types → Constructors → … then Aggregate, Errors). Default alphabetical order had put Aggregate (all/allFromDict) first, burying the core surface.
• New guide section. Why unthrown? gains "Why this matters more with AI in the loop": explicit errors move failure detection to author-time type checking (shortening the LLM generate→run→retry loop), and the defect channel keeps E a precise contract worth checking.

No runtime or public-type changes — index.ts is net-unchanged; types.ts is a one-line doc tweak. Changeset is patch.

Verification

All gates green: format --check, lint, typecheck, knip, test, build. build:docs is warning-free and the VitePress site builds cleanly (the API→guide dead-link check passes).

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes a documentation gap in the @unthrown/core generated API reference by giving the Result/AsyncResult fluent combinator method surface a dedicated, exportable TypeDoc “home”, and by reordering categories so the core surface is easier to find.

Changes:

• Export and document ResultMethods<T, E> and introduce/export AsyncResultMethods<T, E> so TypeDoc can render the fluent combinator tables.
• Configure TypeDoc category ordering to prioritize core API sections (Facade/Types/Constructors/Interop/…).
• Extend the “Why unthrown?” guide and contributor docs, and add a changeset for the new public type exports.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/core/typedoc.json	Adds explicit categoryOrder and stops excluding ResultMethods from generated docs.
packages/core/src/types.ts	Makes ResultMethods public and factors async combinators into AsyncResultMethods for documentation.
packages/core/src/index.ts	Re-exports ResultMethods and AsyncResultMethods as public type exports.
packages/core/src/facade.ts	Cross-links Result/AsyncResult docs to the new method-surface types.
docs/guide/why-unthrown.md	Adds a new guide section explaining the value of explicit errors with AI-assisted development.
CLAUDE.md	Updates contributor documentation to reflect the new TypeDoc structure and exported method-surface types.
.changeset/document-combinator-surface.md	Adds a minor changeset documenting the new public type exports and doc improvements.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.