refactor(memoization): drop unused Result type parameter from MemoizeOptions

`MemoizeOptions<Args, _Result>` had a second type parameter that
was declared but never referenced in the type body — the
underscore prefix advertised "intentionally unused", but the
parameter had no purpose and misled readers into thinking the
options were result-type-aware.

Callers (`Memoize` decorator, `memoize`, `memoizeAsync`) all passed
their own `Result` generic through, which was silently discarded.
Drop the parameter and update the three call sites.

No runtime change; no API change for consumers who wrote
`MemoizeOptions<[string]>` (the default `= unknown` covered them);
consumers who explicitly wrote `MemoizeOptions<Args, Result>` need
to drop the second argument. The type was public but the second
parameter was never load-bearing for anyone.

Author: jdalton

src/memoization.ts

@@ -13,7 +13,7 @@ const cacheRegistry: Array<() => void> = []
 /**
  * Options for memoization behavior.
  */
-export type MemoizeOptions<Args extends unknown[], _Result = unknown> = {
+export type MemoizeOptions<Args extends unknown[]> = {
   /** Custom cache key generator (defaults to JSON.stringify) */
   keyGen?: (...args: Args) => string
   /** Maximum cache size (LRU eviction when exceeded) */
@@ -99,7 +99,7 @@ export function clearAllMemoizationCaches(): void {
  *   }
  * }
  */
-export function Memoize(options: MemoizeOptions<unknown[], unknown> = {}) {
+export function Memoize(options: MemoizeOptions<unknown[]> = {}) {
   return (
     _target: unknown,
     propertyKey: string,
@@ -137,7 +137,7 @@ export function Memoize(options: MemoizeOptions<unknown[], unknown> = {}) {
  */
 export function memoize<Args extends unknown[], Result>(
   fn: (...args: Args) => Result,
-  options: MemoizeOptions<Args, Result> = {},
+  options: MemoizeOptions<Args> = {},
 ): (...args: Args) => Result {
   const {
     keyGen = (...args) => defaultKeyGen(args),
@@ -244,7 +244,7 @@ export function memoize<Args extends unknown[], Result>(
  */
 export function memoizeAsync<Args extends unknown[], Result>(
   fn: (...args: Args) => Promise<Result>,
-  options: MemoizeOptions<Args, Result> = {},
+  options: MemoizeOptions<Args> = {},
 ): (...args: Args) => Promise<Result> {
   const {
     keyGen = (...args) => defaultKeyGen(args),