102 comptime obligation leak

// PINS: an obligation raised inside comptime code is checked. Today it is not —
// it is ERASED before any checker looks.
//
// MEASURED 2026-07-31, and this is not what the pin said before. The old reading
// was "checked but too late" (rejected after the sink had already printed during
// compilation). That is no longer the behavior. Today:
//
//   - the compile succeeds, silently;
//   - nothing is printed during compilation;
//   - `./a.out` prints "comptime input" at RUNTIME.
//
// The mechanism, isolated by probe:
//
//   1. Drop `[comptime]` from the tor DECL and the identical program IS
//      refused — "error[KORU030]: Resource 's' obligation <unsanitized!> was not
//      discharged. No tor accepts <!unsanitized>." So the checker works.
//   2. With `[comptime]` on the decl, `comptime_eval.flowIsFoldable`
//      (comptime_eval.zig:851) matches this flow: a `[comptime]` head with a
//      bare-return impl. `Folder.foldFlow` (comptime_eval.zig:717) evaluates
//      `get-input` to the literal, SUBSTITUTES it into the residue continuation,
//      and promotes that continuation to the flow root.
//   3. The binding `s` — the thing that carried `<unsanitized!>` — no longer
//      exists. What survives is `print.ln("comptime input")`, an ordinary
//      runtime flow with no obligation in it.
//   4. `fold-comptime` runs inside `elaborate` (compiler.kz:1220), and every
//      obligation pass runs inside `analysis` (compiler.kz:1226), which is
//      strictly after. There is nothing left for them to check.
//
// So the ruled fix still stands and is now better motivated: run the SAME
// obligation passes as an elaborate segment scoped to `[comptime]` items BEFORE
// the fold, with a comptime-scoped auto-discharge ahead of them. One
// implementation of obligation semantics, two executions — and constant folding
// can never delete a debt on its way past.
//
// The NOT_CONTAINS assertion is kept: whatever rejects this must reject it
// before the sink can produce output. It passes vacuously today (the print is
// residue, emitted rather than run), and it must keep passing once the check
// moves ahead of evaluation.

~import std/io

~[comptime] pub tor get-input {} -> string<unsanitized!>

~[comptime] get-input -> "comptime input"

~[comptime] get-input(): s |> std/io:print.ln(s)