feat(cluster): use tuple types for common size constants (#389)

Author: fResult

.github/next-minor.md

@@ -10,4 +10,6 @@ https://github.com/radashi-org/radashi/pull/388
 
 ## New Features
 
-####
+#### Improve `cluster` type inference
+
+https://github.com/radashi-org/radashi/pull/389

docs/array/cluster.mdx

@@ -34,3 +34,30 @@ _.cluster(gods, 3)
 //   ['Athena']
 // ]
 ```
+
+### Type Inference
+
+The `cluster` function provides precise type inference for common cluster sizes (1-8):
+
+```ts
+// With explicit size parameter
+const result1 = _.cluster(['a', 'b', 'c'], 1)
+//    ^? [string][]
+
+const result2 = _.cluster(['a', 'b', 'c', 'd'], 2)
+//    ^? [string, string][]
+
+const result3 = _.cluster(['a', 'b', 'c', 'd', 'e', 'f'], 3)
+//    ^? [string, string, string][]
+
+// Using default size parameter (2)
+const defaultSize = _.cluster(['a', 'b', 'c', 'd'])
+//    ^? [string, string][]
+
+// For sizes > 8, falls back to string[][]
+const largeSize = _.cluster(['a', 'b', 'c', 'd'], 10)
+//    ^? string[][]
+
+const veryLargeSize = _.cluster(['a', 'b', 'c', 'd'], 10000)
+//    ^? string[][]
+```

src/array/cluster.ts

@@ -9,10 +9,31 @@
  * ```
  * @version 12.1.0
  */
-export function cluster<T>(array: readonly T[], size = 2): T[][] {
+export function cluster<T, Size extends number = 2>(
+  array: readonly T[],
+  size: Size = 2 as Size,
+): Cluster<T, Size>[] {
   const clusters: T[][] = []
   for (let i = 0; i < array.length; i += size) {
     clusters.push(array.slice(i, i + size))
   }
-  return clusters
+  return clusters as Cluster<T, Size>[]
 }
+
+type Cluster<T, Size extends number> = Size extends 1
+  ? [T]
+  : Size extends 2
+    ? [T, T]
+    : Size extends 3
+      ? [T, T, T]
+      : Size extends 4
+        ? [T, T, T, T]
+        : Size extends 5
+          ? [T, T, T, T, T]
+          : Size extends 6
+            ? [T, T, T, T, T, T]
+            : Size extends 7
+              ? [T, T, T, T, T, T, T]
+              : Size extends 8
+                ? [T, T, T, T, T, T, T, T]
+                : T[]