Refactor attachment cropping functionality to support multiple variants

- Introduced AttachmentCrop model to manage crop variants for attachments.
- Updated Attachment model to remove direct crop fields and establish relationships with AttachmentCrop.
- Modified AttachmentService to handle storing and updating multiple crop variants (desktop and mobile).
- Adjusted validation rules to accommodate new crop structure.
- Updated database migration to create attachment_crops table and migrate existing crop data.
- Refactored tests to ensure compatibility with the new cropping structure and validate multiple crop variants.
- Enhanced documentation to reflect changes in attachment handling and cropping capabilities.

app/Domains/Shared/Rules/CroppedImageOrBase64Rule.php

@@ -35,6 +35,24 @@ class CroppedImageOrBase64Rule implements ValidationRule
             return;
         }
 
+        if (isset($value['crops']) && is_array($value['crops'])) {
+            foreach (['desktop', 'mobile'] as $variant) {
+                $crop = $value['crops'][$variant] ?? null;
+
+                if (! is_array($crop)) {
+                    $fail("The :attribute.crops.{$variant} field must be an object.");
+
+                    continue;
+                }
+
+                $this->validateRange("{$attribute}.crops.{$variant}", 'crop_horizontal', $crop, $fail);
+                $this->validateRange("{$attribute}.crops.{$variant}", 'crop_vertical', $crop, $fail);
+            }
+
+            return;
+        }
+
+        // Backwards compatibility with the original single-crop payload.
         $this->validateRange($attribute, 'crop_horizontal', $value, $fail);
         $this->validateRange($attribute, 'crop_vertical', $value, $fail);
     }