Refactor Array module: new helpers, breaking changes

Refactored the Array module with improved naming, removed isNonEmptyReadonlyArray (use isNonEmptyArray for both mutable and readonly arrays), and renamed mutation helpers to shiftFromArray and popFromArray. Added new helpers: flatMapArray, concatArrays, sortArray, reverseArray, and spliceArray, all with type-safe signatures and non-empty array preservation. Updated tests to cover new and changed APIs.

Author: steida

.changeset/array-module-refactor.md

@@ -0,0 +1,48 @@
+---
+"@evolu/common": major
+---
+
+Refactored the Array module with breaking changes, better naming, and new helpers.
+
+### Breaking Changes
+
+**Removed `isNonEmptyReadonlyArray`** — use `isNonEmptyArray` instead. The function now handles both mutable and readonly arrays via overloads:
+
+```ts
+// Before
+if (isNonEmptyReadonlyArray(readonlyArr)) { ... }
+if (isNonEmptyArray(mutableArr)) { ... }
+
+// After — one function for both
+if (isNonEmptyArray(readonlyArr)) { ... }
+if (isNonEmptyArray(mutableArr)) { ... }
+```
+
+**Renamed mutation functions** for consistency with the `...Array` suffix pattern:
+
+- `shiftArray` → `shiftFromArray`
+- `popArray` → `popFromArray`
+
+### New Functions
+
+- **`flatMapArray`** — maps each element to an array and flattens the result, preserving non-empty type when applicable
+- **`concatArrays`** — concatenates two arrays, returning non-empty when at least one input is non-empty
+- **`sortArray`** — returns a new sorted array (wraps `toSorted`), preserving non-empty type
+- **`reverseArray`** — returns a new reversed array (wraps `toReversed`), preserving non-empty type
+- **`spliceArray`** — returns a new array with elements removed/replaced (wraps `toSpliced`)
+
+### Migration
+
+```ts
+// isNonEmptyReadonlyArray → isNonEmptyArray
+-import { isNonEmptyReadonlyArray } from "@evolu/common";
++import { isNonEmptyArray } from "@evolu/common";
+
+// shiftArray → shiftFromArray
+-import { shiftArray } from "@evolu/common";
++import { shiftFromArray } from "@evolu/common";
+
+// popArray → popFromArray
+-import { popArray } from "@evolu/common";
++import { popFromArray } from "@evolu/common";
+```