Refactor code structure for improved readability and maintainability

docs/api/blog.md

@@ -94,17 +94,19 @@ Create a new blog post.
   "body": "<p>محتوای کامل مقاله...</p>",
   "summary": "خلاصه کوتاه از مقاله",
   "tags": [1, 2],
-  "status": "draft"
+  "status": "draft",
+  "image_url": "/uploads/blogs/blog_abc.jpg"
 }
 ```
 
 | Field | Type | Required | Description |
 |-------|------|----------|-------------|
 | `title` | string | ✅ | Post title (slug auto-generated) |
-| `body` | string | ✅ | Full HTML body |
+| `body` | string | ✅ | Full HTML body (from the admin CKEditor) |
 | `summary` | string | ❌ | Short excerpt |
 | `tags` | integer[] | ❌ | Array of tag IDs |
 | `status` | string | ❌ | `"draft"` (default) or `"published"` |
+| `image_url` | string | ❌ | Cover image path returned by the upload endpoint |
 
 ### Response `201`
 ```json
@@ -158,11 +160,12 @@ Update a blog post.
   "body": "<p>محتوای جدید</p>",
   "summary": "خلاصه جدید",
   "tags": [1, 3],
-  "status": "published"
+  "status": "published",
+  "image_url": "/uploads/blogs/blog_abc.jpg"
 }
 ```
 
-All fields optional.
+All fields optional. Send `image_url: ""` to clear the cover image.
 
 ### Response `200`
 Updated blog object.