feat(Sora): 完成Sora网关接入与媒体能力

新增 Sora 网关路由、账号调度与同步服务\n补充媒体代理与签名 URL、模型列表动态拉取\n完善计费配置、前端支持与相关测试

backend/internal/service/sora_media_sign.go

@@ -0,0 +1,42 @@
+package service
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"strconv"
+	"strings"
+)
+
+// SignSoraMediaURL 生成 Sora 媒体临时签名
+func SignSoraMediaURL(path string, query string, expires int64, key string) string {
+	key = strings.TrimSpace(key)
+	if key == "" {
+		return ""
+	}
+	mac := hmac.New(sha256.New, []byte(key))
+	mac.Write([]byte(buildSoraMediaSignPayload(path, query)))
+	mac.Write([]byte("|"))
+	mac.Write([]byte(strconv.FormatInt(expires, 10)))
+	return hex.EncodeToString(mac.Sum(nil))
+}
+
+// VerifySoraMediaURL 校验 Sora 媒体签名
+func VerifySoraMediaURL(path string, query string, expires int64, signature string, key string) bool {
+	signature = strings.TrimSpace(signature)
+	if signature == "" {
+		return false
+	}
+	expected := SignSoraMediaURL(path, query, expires, key)
+	if expected == "" {
+		return false
+	}
+	return hmac.Equal([]byte(signature), []byte(expected))
+}
+
+func buildSoraMediaSignPayload(path string, query string) string {
+	if strings.TrimSpace(query) == "" {
+		return path
+	}
+	return path + "?" + query
+}