feat: 算力引擎 Go 后端核心（new-api）

- 统一 OpenAI 兼容 /v1 中继 + 渠道/额度/令牌/流水
- 各领域包：relay 模型网关、model 数据层、controller 管理 API

relay/chat_completions_via_responses_test.go

@@ -0,0 +1,71 @@
+package relay
+
+import (
+	"math"
+	"testing"
+
+	relaycommon "github.com/QuantumNous/new-api/relay/common"
+	"github.com/QuantumNous/new-api/types"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIsResponsesEventStreamContentType(t *testing.T) {
+	tests := []struct {
+		name        string
+		contentType string
+		want        bool
+	}{
+		{name: "plain", contentType: "text/event-stream", want: true},
+		{name: "mixed case with charset", contentType: "Text/Event-Stream; charset=utf-8", want: true},
+		{name: "json", contentType: "application/json", want: false},
+		{name: "empty", contentType: "", want: false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, isResponsesEventStreamContentType(tt.contentType))
+		})
+	}
+}
+
+func TestRecalcQuotaFromRatiosIgnoresInvalidMultipliers(t *testing.T) {
+	info := &relaycommon.RelayInfo{
+		PriceData: types.PriceData{
+			Quota: 100,
+		},
+	}
+	info.PriceData.AddOtherRatio("duration", 2)
+
+	quota, ok := recalcQuotaFromRatios(info, map[string]float64{
+		"duration": 3,
+		"zero":     0,
+		"negative": -1,
+		"nan":      math.NaN(),
+		"inf":      math.Inf(1),
+	})
+
+	require.True(t, ok)
+	assert.Equal(t, 150, quota)
+	assert.True(t, info.PriceData.HasOtherRatio("duration"))
+}
+
+func TestRecalcQuotaFromRatiosRejectsAllInvalidAdjustedRatios(t *testing.T) {
+	info := &relaycommon.RelayInfo{
+		PriceData: types.PriceData{
+			Quota: 100,
+		},
+	}
+	info.PriceData.AddOtherRatio("duration", 2)
+
+	quota, ok := recalcQuotaFromRatios(info, map[string]float64{
+		"zero":     0,
+		"negative": -1,
+		"nan":      math.NaN(),
+		"inf":      math.Inf(1),
+	})
+
+	require.False(t, ok)
+	assert.Equal(t, 0, quota)
+	assert.True(t, info.PriceData.HasOtherRatio("duration"))
+}