♻️ Keep the public API to the four factories

The builder types are already the inferred return types and travel into
the emitted .d.ts, so exporting them only made them nameable while
pinning the internal Strict/Widening split as API. Revert the type
exports and the public renames, drop the type-surface test, and document
only the factories in README and development/library.md.

CHANGELOG.md

@@ -7,10 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- export the matcher builder types from the entry point —
-  `PrimitiveUnionMatcher` / `PrimitiveUnionMatcherW`, `TaggedUnionMatcher` /
-  `TaggedUnionMatcherW`, and the tagged-union factory types — and add TSDoc to
-  every public symbol
+- add TSDoc to the four public matcher factories
 - document the public API in the README
 
 ## [0.8.1] - 2026-09-23