fix(ui): use translations for canvas layer select (#6357)

## Summary

Use translations instead of plain strings.

## Related Issues / Discussions


https://discord.com/channels/1020123559063990373/1054129386447716433/1239181243078279208

## QA Instructions

The layer select should still work.

## Merge Plan

n/a

## Checklist

- [x] _The PR has a short but descriptive title, suitable for a
changelog_
- [ ] _Tests added / updated (if applicable)_
- [ ] _Documentation added / updated (if applicable)_

invokeai/frontend/web/src/features/canvas/components/IAICanvasToolbar/IAICanvasToolbar.tsx

@@ -21,7 +21,6 @@ import {
   setShouldShowBoundingBox,
 } from 'features/canvas/store/canvasSlice';
 import type { CanvasLayer } from 'features/canvas/store/canvasTypes';
-import { LAYER_NAMES_DICT } from 'features/canvas/store/canvasTypes';
 import { memo, useCallback, useMemo } from 'react';
 import { useHotkeys } from 'react-hotkeys-hook';
 import { useTranslation } from 'react-i18next';
@@ -216,13 +215,20 @@ const IAICanvasToolbar = () => {
     [dispatch, isMaskEnabled]
   );
 
-  const value = useMemo(() => LAYER_NAMES_DICT.filter((o) => o.value === layer)[0], [layer]);
+  const layerOptions = useMemo<{ label: string; value: CanvasLayer }[]>(
+    () => [
+      { label: t('unifiedCanvas.base'), value: 'base' },
+      { label: t('unifiedCanvas.mask'), value: 'mask' },
+    ],
+    [t]
+  );
+  const layerValue = useMemo(() => layerOptions.filter((o) => o.value === layer)[0] ?? null, [layer, layerOptions]);
 
   return (
     <Flex alignItems="center" gap={2} flexWrap="wrap">
       <Tooltip label={`${t('unifiedCanvas.layer')} (Q)`}>
         <FormControl isDisabled={isStaging} w="5rem">
-          <Combobox value={value} options={LAYER_NAMES_DICT} onChange={handleChangeLayer} />
+          <Combobox value={layerValue} options={layerOptions} onChange={handleChangeLayer} />
         </FormControl>
       </Tooltip>
 

invokeai/frontend/web/src/features/canvas/store/canvasTypes.ts

@@ -5,11 +5,6 @@ import { z } from 'zod';
 
 export type CanvasLayer = 'base' | 'mask';
 
-export const LAYER_NAMES_DICT: { label: string; value: CanvasLayer }[] = [
-  { label: 'Base', value: 'base' },
-  { label: 'Mask', value: 'mask' },
-];
-
 const zBoundingBoxScaleMethod = z.enum(['none', 'auto', 'manual']);
 export type BoundingBoxScaleMethod = z.infer<typeof zBoundingBoxScaleMethod>;
 export const isBoundingBoxScaleMethod = (v: unknown): v is BoundingBoxScaleMethod =>