feat(dev): fake 渠道按 metadata.render 出 redirect/qr/crypto_address 三态

联调 pangolin /buy 页付款类型选择器：Create 读 req.Metadata["render"]
分支返回三种渲染形态的 payload，method 仍是 fake，不新增渠道名，
provider_ref 生成/VerifyCallback/结算逻辑不变。

internal/provider/fake/fake.go

@@ -67,16 +67,42 @@ func (p *Provider) Create(_ context.Context, req provider.CreateRequest) (*provi
 	p.mu.Unlock()
 	exp := time.Now().Add(15 * time.Minute)
 	ref := "FAKE-" + req.OutTradeNo + "-" + strconv.FormatInt(time.Now().UnixNano(), 36)
-	return &provider.Session{
-		ProviderRef: ref,
-		RenderType:  provider.RenderCryptoAddress,
-		Payload: map[string]any{
-			"address":      "TFake" + req.Account.AccountID + req.OutTradeNo,
-			"amount_minor": req.AmountMinor,
-			"currency":     req.Currency,
-		},
-		ExpiresAt: &exp,
-	}, nil
+
+	// render 由 metadata["render"] 驱动(pangolin /buy 联调门控,见 CLAUDE.md 交代);
+	// 只影响这里的展示形态,不影响 provider_ref 生成/VerifyCallback/结算。
+	switch req.Metadata["render"] {
+	case string(provider.RenderRedirect):
+		return &provider.Session{
+			ProviderRef: ref,
+			RenderType:  provider.RenderRedirect,
+			Payload: map[string]any{
+				"url": "http://localhost:8090/result?out_trade_no=" + req.OutTradeNo,
+			},
+			ExpiresAt: &exp,
+		}, nil
+	case string(provider.RenderQR):
+		return &provider.Session{
+			ProviderRef: ref,
+			RenderType:  provider.RenderQR,
+			Payload: map[string]any{
+				"qr_content":     "weixin://wxpay/mock/" + req.OutTradeNo,
+				"display_amount": strconv.FormatInt(req.AmountMinor, 10),
+				"currency":       req.Currency,
+			},
+			ExpiresAt: &exp,
+		}, nil
+	default:
+		return &provider.Session{
+			ProviderRef: ref,
+			RenderType:  provider.RenderCryptoAddress,
+			Payload: map[string]any{
+				"address":      "TFake" + req.Account.AccountID + req.OutTradeNo,
+				"amount_minor": req.AmountMinor,
+				"currency":     req.Currency,
+			},
+			ExpiresAt: &exp,
+		}, nil
+	}
 }
 
 // VerifyCallback 解析测试注入的 JSON 回调体成归一化 PaidEvent。