Refa: http API create dataset and test cases (#7393)

### What problem does this PR solve?

This PR introduces Pydantic-based validation for the create dataset HTTP
API, improving code clarity and robustness. Key changes include:
1. Pydantic Validation
2. ​​Error Handling
3. Test Updates
4. Documentation

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] Documentation Update
- [x] Refactoring

sdk/python/test/test_sdk_api/t_dataset.py

@@ -14,10 +14,11 @@
 #  limitations under the License.
 #
 
-from ragflow_sdk import RAGFlow
 import random
+
 import pytest
 from common import HOST_ADDRESS
+from ragflow_sdk import RAGFlow
 
 
 def test_create_dataset_with_name(get_api_key_fixture):
@@ -32,7 +33,7 @@ def test_create_dataset_with_duplicated_name(get_api_key_fixture):
     rag.create_dataset("test_create_dataset_with_duplicated_name")
     with pytest.raises(Exception) as exc_info:
         rag.create_dataset("test_create_dataset_with_duplicated_name")
-    assert str(exc_info.value) == "Duplicated dataset name in creating dataset."
+    assert str(exc_info.value) == "Dataset name 'test_create_dataset_with_duplicated_name' already exists"
 
 
 def test_create_dataset_with_random_chunk_method(get_api_key_fixture):
@@ -46,11 +47,13 @@ def test_create_dataset_with_random_chunk_method(get_api_key_fixture):
 def test_create_dataset_with_invalid_parameter(get_api_key_fixture):
     API_KEY = get_api_key_fixture
     rag = RAGFlow(API_KEY, HOST_ADDRESS)
-    valid_chunk_methods = ["naive", "manual", "qa", "table", "paper", "book", "laws", "presentation", "picture", "one", "email", "tag"]
     chunk_method = "invalid_chunk_method"
     with pytest.raises(Exception) as exc_info:
         rag.create_dataset("test_create_dataset_with_invalid_chunk_method", chunk_method=chunk_method)
-    assert str(exc_info.value) == f"'{chunk_method}' is not in {valid_chunk_methods}"
+    assert (
+        str(exc_info.value)
+        == f"Field: <chunk_method> - Message: <Input should be 'naive', 'book', 'email', 'laws', 'manual', 'one', 'paper', 'picture', 'presentation', 'qa', 'table' or 'tag'> - Value: <{chunk_method}>"
+    )
 
 
 def test_update_dataset_with_name(get_api_key_fixture):