feat: 新增支持codex转发

backend/internal/service/ports/openai_oauth.go

@@ -0,0 +1,13 @@
+package ports
+
+import (
+	"context"
+
+	"sub2api/internal/pkg/openai"
+)
+
+// OpenAIOAuthClient interface for OpenAI OAuth operations
+type OpenAIOAuthClient interface {
+	ExchangeCode(ctx context.Context, code, codeVerifier, redirectURI, proxyURL string) (*openai.TokenResponse, error)
+	RefreshToken(ctx context.Context, refreshToken, proxyURL string) (*openai.TokenResponse, error)
+}