core/runtime: DeepSeek default base URL without /v1

Use https://api.deepseek.com as the empty-url default for deepseek preset.

doc/plyngent.example.toml

@@ -40,7 +40,7 @@ access_key_or_token = "sk-replace-me"
 # [providers.deepseek]
 # preset = "deepseek"
 # access_key_or_token = "sk-replace-me"
-# # url defaults to https://api.deepseek.com/v1 when empty
+# # url defaults to https://api.deepseek.com when empty
 # extras = { convention = "openai" }
 #
 # [providers.deepseek.models]

src/plyngent/runtime/client_factory.py

@@ -15,7 +15,7 @@ if TYPE_CHECKING:
     from collections.abc import Mapping
 
 DEFAULT_OPENAI_BASE_URL = "https://api.openai.com/v1"
-DEFAULT_DEEPSEEK_BASE_URL = "https://api.deepseek.com/v1"
+DEFAULT_DEEPSEEK_BASE_URL = "https://api.deepseek.com"
 
 type OpenAICompatibleClient = OpenAIClient | DeepseekOpenAIClient
 

tests/test_runtime/test_client_factory.py

@@ -42,7 +42,7 @@ def test_deepseek_openai_convention() -> None:
     provider = DeepseekProvider(access_key_or_token="sk-test")
     client = create_client(provider)
     assert isinstance(client, DeepseekOpenAIClient)
-    assert provider_to_openai_config(provider).base_url == "https://api.deepseek.com/v1"
+    assert provider_to_openai_config(provider).base_url == "https://api.deepseek.com"
     assert "deepseek-v4-flash" in provider.models
     assert "deepseek-v4-pro" in provider.models