iter loop-recur.tidy GREEN: reject lambda-captures-loop-binder at check + milestone-close audit resolution

GREEN side of the RED audit-trail commit 39380d3. The loop/recur
milestone-close audit found a [high] correctness defect — a lambda
capturing a loop binder passed `ail check` then panicked
unreachable!() at codegen (crates/ailang-codegen/src/lambda.rs:102)
on type-correct input. Fixed symmetrically to mut.4-tidy: new
CheckError::LoopBinderCapturedByLambda (code
loop-binder-captured-by-lambda, bracket-free F2 Display), the
Term::Lam escape guard gained a parallel loop_stack pass. Minimal
mechanism: loop_stack element Vec<Type> -> Vec<(String,Type)> so
the already-threaded per-loop frame carries binder names; recur
still reads .1 by position (Boss-call-2 positional invariant
preserved verbatim — the name is a second field for the escape
guard only, a consumer iter-2 did not anticipate). Codegen
byte-unchanged (typecheck-only fix). carve_out 17->18 + ct1-F2 +
DESIGN.md note lockstep.

Folded in (Boss-side, audit resolution): the two [medium]
doc-honesty edits the audit surfaced (mut_var_allocas rustdoc now
states its mut-var+loop-binder dual use; Term::Loop doc-comment
now describes the real shipped state, not iter-1's stale
"per-binder phi" forward-look) + a [low] P2 roadmap todo
(plan-recon undercount countermeasure, pairs with planner Step-5
items 7+8). Bench gate: all 3 scripts exit 0, 25 metrics 0
regressed — pristine, carry-on (no baseline/ratify).

cargo test --workspace 619 -> 622 / 0 red (Boss-reran
independently, hash_pin 11/0). The loop/recur milestone is
audit-clean; fieldtest is the only remaining step before close.

bench/orchestrator-stats/2026-05-17-iter-loop-recur.tidy.json

@@ -0,0 +1,12 @@
+{
+  "iter_id": "loop-recur.tidy",
+  "date": "2026-05-17",
+  "mode": "mini",
+  "outcome": "DONE",
+  "tasks_total": 1,
+  "tasks_completed": 1,
+  "reloops_per_task": { "1": 0 },
+  "review_loops_spec": 0,
+  "review_loops_quality": 0,
+  "blocked_reason": null
+}