feat(distribution): 移除生产环境资金冻结，测试与生产口径统一

liveMoneyMovementEnabled 按 APP_ENV 在生产冻结结算入账、站点提现与自动释放，
与测试环境行为不一致，且该开关在 APP_ENV 缺失时为 fail-open。本次整体移除：

- 删除 liveMoneyMovementEnabled 与 ErrLiveMoneyMovementFrozen
- MarkSettlementBatch / ApplySiteWithdrawal / AutoReleaseDueSettlements 去掉守卫
- handler 去掉 403 settlement_frozen 映射
- 测试改为断言生产环境结算入账与提现正常执行

backend/internal/modules/distribution/handler.go

@@ -787,8 +787,6 @@ func writeError(c *gin.Context, err error) {
 		response.BadRequest(c, "请选择要加价的商品")
 	case errors.Is(err, ErrInvalidListingStatus):
 		response.BadRequest(c, "商品展示状态不正确")
-	case errors.Is(err, ErrLiveMoneyMovementFrozen):
-		response.Error(c, http.StatusForbidden, "settlement_frozen", "分销结算与提现已冻结，待分成口径确认后再开放")
 	case errors.Is(err, ErrSiteAccessDenied):
 		response.Error(c, http.StatusForbidden, "forbidden", "无权访问该分销站点")
 	case errors.Is(err, ErrDependencyUnavailable):