feat(Plate): add coordinateSystemSize utility function

Add a new utility function that calculates the total number of positions
in a coordinate system (rows.length * columns.length). Use it to simplify
allCoordinateSystemPositions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: spawnia

src/Plate/utils.test.tsx

@@ -10,6 +10,7 @@ import {
   columnForPosition,
   convertPositionFromColumnToRowFlow,
   convertPositionFromRowToColumnFlow,
+  coordinateSystemSize,
   ensureCoordinatesInRange,
   rowForPosition,
 } from './utils';
@@ -176,6 +177,13 @@ const COORDINATE_SYSTEM_2_BY_2 = {
   columns: [1, 2],
 } as const satisfies CoordinateSystem;
 
+describe('coordinateSystemSize', () => {
+  it('returns the total number of positions in a coordinate system', () => {
+    expect(coordinateSystemSize(COORDINATE_SYSTEM_2_BY_2)).toBe(4);
+    expect(coordinateSystemSize(COORDINATE_SYSTEM_12X8)).toBe(96);
+  });
+});
+
 describe('allCoordinateSystemPositions', () => {
   it('returns an array of all positions in a coordinate systems', () => {
     expect(allCoordinateSystemPositions(COORDINATE_SYSTEM_2_BY_2)).toEqual([

src/Plate/utils.ts

@@ -164,13 +164,16 @@ export function assertUniquePositions(
   }
 }
 
+export function coordinateSystemSize(
+  coordinateSystem: CoordinateSystem,
+): number {
+  return coordinateSystem.rows.length * coordinateSystem.columns.length;
+}
+
 export function allCoordinateSystemPositions(
   coordinateSystem: CoordinateSystem,
 ): Array<number> {
-  return range(
-    1,
-    coordinateSystem.rows.length * coordinateSystem.columns.length + 1,
-  );
+  return range(1, coordinateSystemSize(coordinateSystem) + 1);
 }
 
 export function allCoordinateSystemCoordinates<