feat(api): add unified index API and dataset management endpoints (#14222)

### What problem does this PR solve?

## Summary

Refactor the dataset API layer into a clean service/REST separation
pattern, add a unified `/index` API for graph/raptor/mindmap operations,
and introduce several new dataset management endpoints with full test
coverage.

## Changes

### Service Layer (`dataset_api_service.py`)

- Added `trace_index(dataset_id, tenant_id, index_type)` — unified trace
function for all index types
- Added `run_index`, `delete_index` service functions
- Added `get_dataset`, `get_ingestion_summary`, `list_ingestion_logs`,
`get_ingestion_log`
- Added `run_embedding`, `list_tags`, `aggregate_tags`, `delete_tags`,
`rename_tag`
- Added `get_flattened_metadata`, `get_auto_metadata`,
`update_auto_metadata`

### REST API Layer (`dataset_api.py`)

**New unified routes:**

| Method | Route | Description |
|--------|-------|-------------|
| POST | `/datasets/<id>/index?type=graph\|raptor\|mindmap` | Run index
task |
| GET | `/datasets/<id>/index?type=graph\|raptor\|mindmap` | Trace index
task |
| DELETE | `/datasets/<id>/<index_type>` | Delete index |
| GET | `/datasets/<id>` | Get dataset details |
| GET | `/datasets/<id>/ingestions/summary` | Ingestion summary |
| GET | `/datasets/<id>/ingestions` | List ingestion logs |
| GET | `/datasets/<id>/ingestions/<log_id>` | Get single ingestion log
|
| POST | `/datasets/<id>/embedding` | Run embedding |
| GET | `/datasets/<id>/tags` | List tags |
| GET | `/datasets/tags/aggregation` | Aggregate tags across datasets |
| DELETE | `/datasets/<id>/tags` | Delete tags |
| PUT | `/datasets/<id>/tags` | Rename tag |
| GET | `/datasets/metadata/flattened` | Get flattened metadata |
| GET/PUT | `/datasets/<id>/metadata/config` | New metadata config path
|

**Removed routes (replaced by unified `/index`):**

- `POST /datasets/<id>/mindmap`
- `GET /datasets/<id>/mindmap`

**Preserved legacy routes (backward compatibility):**

- `/run_graphrag`, `/trace_graphrag`, `/run_raptor`, `/trace_raptor`
- `/auto_metadata` GET/PUT

### Test Suite

- Updated `common.py` helpers: added `trace_index`, removed
`run_mindmap`/`trace_mindmap`
- Added 7 new test files with 39 test cases total:

| Test File | Cases |
|-----------|-------|
| `test_get_dataset.py` | 4 |
| `test_ingestion_summary.py` | 2 |
| `test_ingestion_logs.py` | 5 |
| `test_index_api.py` | 14 |
| `test_embedding.py` | 2 |
| `test_tags.py` | 8 |
| `test_flattened_metadata.py` | 4 |

- Deleted `test_mindmap_tasks.py` (covered by unified index tests)

## Design Decisions

1. **Unified `/index?type=...`** — single endpoint replaces 3 separate
route pairs for graph/raptor/mindmap
2. **Backward compatibility** — old routes (`/run_graphrag`,
`/run_raptor`, `/auto_metadata`) preserved alongside new paths
3. **`_VALID_INDEX_TYPES = {"graph", "raptor", "mindmap"}`** — input
validation via constant set
4. **`_INDEX_TYPE_TO_TASK_ID_FIELD`** — maps index type to KB model task
ID field for clean dispatch

## Files Changed

- `api/apps/restful_apis/dataset_api.py`
- `api/apps/services/dataset_api_service.py`
- `sdk/python/ragflow_sdk/modules/dataset.py`
- `test/testcases/test_http_api/common.py`
- `test/testcases/test_http_api/test_dataset_management/` (7 new files)
### Type of change

- [x] New Feature (non-breaking change which adds functionality)
- [x] Refactoring

---------

Signed-off-by: noob <yixiao121314@outlook.com>

sdk/python/test/test_frontend_api/test_chunk.py

@@ -21,7 +21,7 @@ from timeit import default_timer as timer
 
 def test_parse_txt_document(get_auth):
     # create dataset
-    res = create_dataset(get_auth, "test_parse_txt_document")
+    res = create_dataset(get_auth, {"name": "test_parse_txt_document"})
     assert res.get("code") == 0, f"{res.get('message')}"
 
     # list dataset
@@ -29,8 +29,10 @@ def test_parse_txt_document(get_auth):
     dataset_list = []
     dataset_id = None
     while True:
-        res = list_dataset(get_auth, page_number)
-        data = res.get("data").get("kbs")
+        res = list_dataset(get_auth, {"page": page_number, "page_size": 150})
+        data = res.get("data")
+        if isinstance(data, dict):
+            data = data.get("kbs", [])
         for item in data:
             dataset_id = item.get("id")
             dataset_list.append(dataset_id)
@@ -66,7 +68,7 @@ def test_parse_txt_document(get_auth):
     print('time cost {:.1f}s'.format(timer() - start_ts))
 
     # delete dataset
-    for dataset_id in dataset_list:
-        res = rm_dataset(get_auth, dataset_id)
+    if dataset_list:
+        res = rm_dataset(get_auth, dataset_list)
         assert res.get("code") == 0, f"{res.get('message')}"
     print(f"{len(dataset_list)} datasets are deleted")