📝 Refresh license year, backlog notes and JSDoc

Bump the copyright to 2026 in LICENSE and README, add the
comparison-section notes to the backlog, and trim the primitive-union
factory JSDoc now that the universe rules live in README § Caveats.

src/primitive-union.ts

@@ -97,16 +97,15 @@ const dispatch =
         );
 
 /**
- * Create a matcher for a finite primitive universe, with one common return type.
+ * Create a matcher for a finite primitive universe, with one common return
+ * type.
  *
  * Use it when the value itself is the union (`"yes" | "no"`) and every handler
  * returns the same type.
  *
- * The universe `T` must be a finite union of literals with no
- * value/stringification collision: broad members (`string`, `number`, template
- * literals) and `true | "true"` / `1 | "1"` are rejected at the call site. The
- * returned builder takes a handler map keyed by the members; supplying a second
- * fallback argument allows a partial map and receives the unhandled remainder.
+ * The returned builder takes a handler map keyed by the members; supplying a
+ * second fallback argument allows a partial map and receives the unhandled
+ * remainder.
  *
  * @typeParam T - The finite universe of primitive members to match.
  * @returns A builder for the handler map, or the handler map plus a fallback.