fix: 收窄 OpenAI o 系列模型适配范围 (#5293)

* fix: 收窄 OpenAI o 系列模型适配范围

* fix(openai): 限制 gpt-5 适配仅作用于 OpenAI 模型

* fix(openai): narrow o-series reasoning model detection

---------

Co-authored-by: Seefs <i@seefs.me>

dto/openai_request_zero_value_test.go

@@ -71,3 +71,27 @@ func TestOpenAIResponsesRequestPreserveExplicitZeroValues(t *testing.T) {
 	require.True(t, gjson.GetBytes(encoded, "stream").Exists())
 	require.True(t, gjson.GetBytes(encoded, "top_p").Exists())
 }
+
+func TestGeneralOpenAIRequestGetSystemRoleName(t *testing.T) {
+	tests := []struct {
+		name  string
+		model string
+		want  string
+	}{
+		{name: "o1 uses developer", model: "o1", want: "developer"},
+		{name: "o3 family uses developer", model: "o3-mini-high", want: "developer"},
+		{name: "o4 family uses developer", model: "o4-mini", want: "developer"},
+		{name: "o1 mini stays system", model: "o1-mini", want: "system"},
+		{name: "o1 preview stays system", model: "o1-preview", want: "system"},
+		{name: "gpt 5 uses developer", model: "gpt-5", want: "developer"},
+		{name: "omni is not o series", model: "omni-moderation-latest", want: "system"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := GeneralOpenAIRequest{Model: tt.model}
+
+			require.Equal(t, tt.want, req.GetSystemRoleName())
+		})
+	}
+}