feat(dataset-groups): CRUD, latest-in-group, group SLD with dataset fallback, CreateRasterFromFile

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

README.md

@@ -32,6 +32,9 @@ api/openapi.yaml         OpenAPI 3.1.1 spec (embedded + served at /openapi.yaml)
 
 - **Category** — hierarchical (self-referencing `parent_id`). Full CRUD; cycle-safe
   on update.
+- **DatasetGroup** — a named group of "одноимённые" datasets (see *Dataset
+  groups* below). Full CRUD; deleting a group still referenced by datasets is
+  rejected with 409.
 - **Dataset** — a geo file uploaded to S3/MinIO (`file_type`: `vector_with_kato |
   vector | raster`), belonging to one Category. Carries `code`/`name`/`description`/
   `unit` metadata, a user-defined `meta` (JSONB) blob, an `automated` flag, a
@@ -103,6 +106,26 @@ three are accepted on `POST /datasets` (form fields), `PUT /datasets/{id}` and
 `?start_date_from=`, `?start_date_to=`, `?end_date_from=` and `?end_date_to=`
 (each `YYYY-MM-DD`).
 
+### Dataset groups
+
+A **dataset group** (`/dataset-groups`) collects the datasets that describe the
+same indicator for different periods — the "одноимённые" datasets. A group has a
+slug `code` (unique), a `name` and a `description`, and datasets join it through
+their `dg_id`.
+
+**Freshness.** `GET /dataset-groups/{id}/latest` returns the group's freshest
+dataset: the greatest `end_date` wins, datasets without an `end_date` come last,
+and ties are broken by the newest `created_at`. Narrow the candidates with
+`?status=` and `?file_type=` (for example `?status=ready&file_type=raster` to
+get the latest published raster). A group with no matching dataset yields 404.
+
+**Shared SLD.** A group can carry one SLD (Styled Layer Descriptor) style file
+(`POST`/`GET /dataset-groups/{id}/sld`, multipart `file`, `.sld` or `.xml`),
+which acts as the fallback style for every dataset in the group:
+`GET /datasets/{id}/sld` returns the dataset's own SLD when it has one, and
+otherwise falls back to its group's — 404 only when neither exists. Deleting a
+group also removes its stored SLD object.
+
 ## Getting started
 
 ```sh
@@ -138,7 +161,17 @@ server runs it is served at `/openapi.yaml`, with an interactive **Redoc** UI at
 | GET    | `/datasets/{id}/download`  | download the stored file             |
 | POST   | `/datasets/{id}/mapping`   | set KATO column + year→period map (vector_with_kato) |
 | GET    | `/datasets/{id}/observations` | paginated unpivoted values (`?kato_code=`, `?page=`, `?page_size=`) |
+| POST   | `/datasets/{id}/sld`       | upload/replace the dataset's SLD (multipart `file`, `.sld`/`.xml`) |
+| GET    | `/datasets/{id}/sld`       | download the dataset's SLD, falling back to its group's |
 | DELETE | `/datasets/{id}`           | delete (row + object)                |
+| GET    | `/dataset-groups`          | paginated list (`?code=`, `?page=`, `?page_size=`) |
+| POST   | `/dataset-groups`          | create (`code`, `name`, `description?`) |
+| GET    | `/dataset-groups/{id}`     | get                                  |
+| PUT    | `/dataset-groups/{id}`     | update                               |
+| DELETE | `/dataset-groups/{id}`     | delete (409 while datasets reference it) |
+| GET    | `/dataset-groups/{id}/latest` | freshest dataset of the group (`?status=`, `?file_type=`) |
+| POST   | `/dataset-groups/{id}/sld` | upload/replace the group's shared SLD |
+| GET    | `/dataset-groups/{id}/sld` | download the group's shared SLD      |
 
 Example upload: