feat: Add City entity methods and migration for title field

- Created a new JSON file for the City entity's AST representation, detailing its methods and properties.
- Added a migration to alter the cities table by adding a nullable title column.

docs/api/location.md

@@ -188,6 +188,7 @@ Create a new city.
 |-------|------|----------|-------------|
 | `name` | string | ✅ | City name |
 | `site_name` | string | ❌ | Public site name shown on the city's booking website (e.g. `"یزد نوبت"`) |
+| `title` | string | ❌ | SEO meta title for the city's booking website (e.g. `"نوبت‌دهی آنلاین پزشکان یزد | یزد نوبت"`) |
 | `province_id` | integer | ❌ | Parent province ID |
 | `status` | string | ❌ | `"active"` or `"inactive"` |
 | `weight` | integer | ❌ | Sort weight |