♻️ Align primitive-union matcher names and drop stale lint disables

Rename `MatcherStrict` / `MatcherWidening` to
`PrimitiveUnionMatcherStrict` / `PrimitiveUnionMatcherWidening`, matching
the exported `getPrimitiveUnionMatcher(W)` names and the
`TaggedUnionMatcher*` pair.

Folds in the working-tree lint cleanups: drop the now-unneeded
`typescript/unified-signatures` disables and turn the tagged-union
factory interfaces into type aliases.

src/tagged-union.ts

@@ -102,13 +102,15 @@ interface TaggedUnionMatcherWidening<T extends object, K extends keyof T> {
 // The key-taking step of the curried factory. Naming it lets the factory return
 // `dispatch` directly, the tacit twin of the primitive-union factory's bare
 // `=> dispatch`.
-interface TaggedUnionMatcherFactory<T extends object> {
-    <K extends Discriminated<T>>(k: K): TaggedUnionMatcherStrict<T, K>;
-}
+type TaggedUnionMatcherFactory<T extends object> = <K extends Discriminated<T>>(
+    k: K,
+) => TaggedUnionMatcherStrict<T, K>;
 
-interface TaggedUnionMatcherWideningFactory<T extends object> {
-    <K extends Discriminated<T>>(k: K): TaggedUnionMatcherWidening<T, K>;
-}
+type TaggedUnionMatcherWideningFactory<T extends object> = <
+    K extends Discriminated<T>,
+>(
+    k: K,
+) => TaggedUnionMatcherWidening<T, K>;
 
 const dispatch =
     (k: PropertyKey) =>