Support generated set construction for compact range domains

[pesap]

Problem

Arco needs generated set construction for compact range domains.

Today, top-level set needs explicit members, so something simple becomes verbose.

GAMS:

Sets
   i  rows /i0*i24/
   j  cols /j0*j24/;

Current Arco style is much longer because every member must be listed.

Goal

Support compact range-style set declarations in a KDL-friendly way.

Possible direction:

set i alias=row prefix="i" start=0 end=24
set j alias=col prefix="j" start=0 end=24

Exact syntax open. Main need is compact generated domains without CSV fixtures or giant inline lists.

Acceptance

• compact range-style domains supported
• stays aligned with KDL 2.0.0 and current Arco style
• generated sets work with existing validation and lowering flows

Related

Pairs with parametric analysis inputs, since generated sets get more useful when size can vary.

[pesap]

Follow-up blocked issue: #165. Once generated sets land, this benchmark update can move.