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

controller/rankings.go

@@ -0,0 +1,24 @@
+package controller
+
+import (
+	"net/http"
+
+	"github.com/QuantumNous/new-api/service"
+	"github.com/gin-gonic/gin"
+)
+
+func GetRankings(c *gin.Context) {
+	result, err := service.GetRankingsSnapshot(c.DefaultQuery("period", "week"))
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"success": false,
+			"message": err.Error(),
+		})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"success": true,
+		"data":    result,
+	})
+}