feat: add CategoryImporter service and SeedCategoriesCommand for seeding category data

- Implemented CategoryImporter service to handle bulk export/import logic for categories.
- Created SeedCategoriesCommand to seed category tables from JSON files in data/seed/.
- Added validation and normalization for category data during import.
- Ensured proper error handling and user feedback during the seeding process.

docs/api/category-import.md

@@ -111,3 +111,29 @@ A non-empty array of records, or `{ "items": [ … ] }`. Max **5000** rows.
 | `ERR_IMPORT_TOO_LARGE` | 422 | More than 5000 rows |
 | (field errors) | 422 | One entry per failed row/field; no rows written |
 | `ERR_IMPORT_FAILED` | 500 | DB error during replace (transaction rolled back) |
+
+---
+
+## Seeding a from-scratch database
+
+Canonical category data ships in the repo at `data/seed/*.json`
+(`provinces.json`, `cities.json`, `specialties.json`, `doctor_services.json`).
+After creating an empty schema, populate it with:
+
+```bash
+ddev exec php bin/console app:seed-categories
+```
+
+The command (`App\Category\Command\SeedCategoriesCommand`) reads those files and
+runs the same strict validation + wipe-and-replace as the HTTP import, in
+dependency order (provinces → cities, specialties → doctor_services). The shared
+logic lives in `App\Category\Service\CategoryImporter`.
+
+Full rebuild:
+```bash
+ddev exec php bin/console doctrine:database:drop --force
+ddev exec php bin/console doctrine:database:create
+ddev exec php bin/console doctrine:migrations:migrate --no-interaction
+ddev exec php bin/console app:seed-categories
+ddev exec php bin/console app:create-admin 09100000001 'Test@1234'
+```