fix(web): cap default images at 5 MiB

packages/attachment/attachment-local/tests/index.spec.ts

@@ -14,6 +14,7 @@ import LocalAttachmentStore, {
 describe('local attachment service', () => {
   it('resolves every omitted admission limit explicitly', () => {
     const service = new LocalAttachmentStore(new Context(), {})
+    expect(DEFAULT_MAX_IMAGE_BYTES).toBe(5 * 1024 * 1024)
     expect(service.imageLimits).toEqual({
       maxImageBytes: DEFAULT_MAX_IMAGE_BYTES,
       maxImagesPerMessage: DEFAULT_MAX_IMAGES_PER_MESSAGE,