feat(merchant): 支付宝直连通道商户配置商户端接口

新增商户端支付宝直连通道商户配置接口, 路径前缀 /mch/alipay/direct-channel-merchant,
提供基础信息查看(含 alipayUserId), 商户号取自 PaymentContext 并校验通道商户归属防越权.

daxpay-channel/daxpay-channel-alipay/src/main/java/cn/daxpay/open/channel/alipay/controller/direct/MchAlipayDirectChannelMerchantController.java

@@ -0,0 +1,70 @@
+package cn.daxpay.open.channel.alipay.controller.direct;
+
+import cn.daxpay.open.channel.alipay.result.direct.AlipayDirectChannelMerchantResult;
+import cn.daxpay.open.channel.alipay.service.direct.AlipayDirectChannelMerchantService;
+import cn.daxpay.open.payment.common.context.PaymentContext;
+import cn.daxpay.open.payment.merchant.dao.channel.ChannelMerchantManager;
+import cn.daxpay.open.payment.merchant.entity.channel.ChannelMerchant;
+import cn.daxpay.open.platform.core.annotation.PermCode;
+import cn.daxpay.open.platform.core.code.CommonCode;
+import cn.daxpay.open.platform.core.code.PermCodes;
+import cn.daxpay.open.platform.core.exception.BizInfoException;
+import cn.daxpay.open.platform.core.rest.Res;
+import cn.daxpay.open.platform.core.rest.result.Result;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.validation.constraints.NotBlank;
+import lombok.RequiredArgsConstructor;
+import org.springframework.validation.annotation.Validated;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.Objects;
+
+/// # 支付宝直连通道商户配置（商户端）
+///
+/// 对照运营端 [AlipayDirectChannelMerchantController]，路径前缀 `/mch/alipay/direct-channel-merchant`。
+/// 提供支付宝直连通道商户的基础信息查看（含支付宝商家识别码 alipayUserId），商户号一律取自 [PaymentContext]，防越权。
+@PermCode(menuCode = PermCodes.Channel.Merchant.MENU)
+@Validated
+@Tag(name = "支付宝直连通道商户配置(商户端)")
+@RestController
+@RequestMapping("/mch/alipay/direct-channel-merchant")
+@RequiredArgsConstructor
+public class MchAlipayDirectChannelMerchantController {
+
+    private final AlipayDirectChannelMerchantService alipayDirectChannelMerchantService;
+    private final ChannelMerchantManager channelMerchantManager;
+    private final PaymentContext paymentContext;
+
+    /// 当前登录商户号（上下文必有；缺则视为会话异常）
+    private String requireMchNo() {
+        String mchNo = paymentContext.getMchNo();
+        if (mchNo == null || mchNo.isBlank()) {
+            // 商户上下文缺失
+            throw new BizInfoException(CommonCode.FAIL_CODE, "pay.error.assist.mchContextMissing");
+        }
+        return mchNo;
+    }
+
+    /// 校验通道商户属于当前商户（防越权）
+    private void assertChannelMchOwned(String channelMchNo) {
+        ChannelMerchant channelMerchant = channelMerchantManager.findByChannelMchNo(channelMchNo)
+                // 支付宝: 通道商户不存在或商户号不匹配
+                .orElseThrow(() -> new BizInfoException(CommonCode.FAIL_CODE, "error.channel.alipay.mchAppNotFound"));
+        if (!Objects.equals(channelMerchant.getMchNo(), this.requireMchNo())) {
+            // 支付宝: 通道商户与商户号不匹配
+            throw new BizInfoException(CommonCode.FAIL_CODE, "error.channel.alipay.mchAppNotFound");
+        }
+    }
+
+    @PermCode(code = PermCodes.Action.VIEW)
+    @Operation(summary = "根据通道商户号查询支付宝直连通道商户配置")
+    @GetMapping("/find-by-channel-mch-no")
+    public Result<AlipayDirectChannelMerchantResult> findByChannelMchNo(
+            @NotBlank(message = "{validation.field.channelMerchantNo.notBlank}") String channelMchNo) {
+        this.assertChannelMchOwned(channelMchNo);
+        return Res.ok(alipayDirectChannelMerchantService.findByChannelMchNo(channelMchNo));
+    }
+}