099 aspire koru template facet

// ASPIRATION — currently RED, a PIN not a regression (never been green).
//
// THE |koru TEMPLATE FACET (ruled 2026-07-04): alongside |zig and |js, a
// template proc can carry a |koru variant whose rendered output is KORU
// SOURCE — Liquid-processed, then parsed by the real parser into AST nodes,
// never spliced as host text. First consumer: the comptime interpreter — in
// a [comptime] context the |koru facet is selected, the rendered impl is
// parsed, evaluated at Stage C, and the value spliced into the residue.
//
// Also encodes the ruled head shape `~[template] proc name|koru`: the
// consumption mode lives in the annotation beside its sibling [transform]
// (control.kz:151), and the pipe path is name|target only. Today's
// `~proc name|template|zig` form (control.kz:35) predates this ruling.
//
// Grounded surface: event/call/bind/fold shape mirrors 310_098 (green);
// Liquid arg substitution mirrors 250_001 (green). ASPIRATIONAL bits: the
// [template] annotation placement, the |koru facet, parse-the-rendering.
~import std/io

~[comptime] pub event double-sum { a: i64, b: i64 } -> i64

~[template] proc double-sum|koru {
    -> ({{ a }} + {{ b }}) * 2
}

~[comptime] double-sum(a: 20, b: 1): r |> std/io:print.ln("{{ r:d }}")