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/channel/openai/stream_tool_billing_test.go

@@ -0,0 +1,27 @@
+package openai
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCollectStreamFunctionCallNamesDedupesSameIndex(t *testing.T) {
+	seen := make(map[string]struct{})
+	var names []string
+
+	chunks := []string{
+		`{"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"c1","type":"function","function":{"name":"get_weather","arguments":""}}]}}]}`,
+		`{"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"function":{"arguments":"{\"q\":"}}]}}]}`,
+		`{"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"function":{"arguments":"\"x\"}"}}]}}]}`,
+		`{"choices":[{"index":0,"delta":{"tool_calls":[{"index":1,"id":"c2","type":"function","function":{"name":"get_time","arguments":""}}]}}]}`,
+		`{"choices":[{"index":0,"delta":{"tool_calls":[{"index":1,"function":{"arguments":"{}"}}]}}]}`,
+	}
+	for _, chunk := range chunks {
+		collectStreamFunctionCallNames(chunk, seen, &names)
+	}
+
+	require.Len(t, names, 2)
+	assert.Equal(t, []string{"get_weather", "get_time"}, names)
+}