…nEval pass@1 ≥86.00% (1.2 pp noise → effective 84.80%) clean-branch rebuild

Wires MODEL-1 `apr eval --benchmark humaneval` ship floor (AC-SHIP1-005)
to a pure two-number threshold verdict fn. Clean-branch rebuild of the
SHIP-005 delta from the now-superseded stacked PR #1015 (commit
8c497a0 which layered on top of SHIP-007 PR #1019 prior to SHIP-002
landing). Re-based directly on current main (f615148) so SHIP-005
stands alone — SHIP-007 (#1019) remains open blocked on infra defect
#1020 (runner-disk-guard cross-runner race) and SHIP-018 (#1004) still
in flight.

MODEL-1 AC-SHIP1 coverage on main: 3/10 touched (SHIP-009 + SHIP-008 +
SHIP-006) pre-SHIP-002; 4/10 once SHIP-002 landed via f615148;
5/10 once this PR lands. Mirrors MODEL-2 SHIP-018 shape (pass@1
threshold) but uniquely carries a 1.2 pp noise allowance called out by
spec §4.2 AC-SHIP1-005 — MODEL-2 has no noise window.

contracts/qwen2-e2e-verification-v1.yaml v1.1.0 → v1.2.0:
  - Adds FALSIFY-QW2E-SHIP-005 binding
      AC_SHIP1_005_NOMINAL_HUMANEVAL_PASS_AT_1_PCT = 86.00
      AC_SHIP1_005_NOISE_ALLOWANCE_PP              = 1.20
      AC_SHIP1_005_EFFECTIVE_HUMANEVAL_PASS_AT_1_PCT ≈ 84.80
    to `verdict_from_pass_at_1(correct, total, threshold_pct) ->
    Ship005Verdict` in `crates/aprender-core/src/metrics/ship_005.rs`.
  - 8-section mutation survey:
      1. Safe-margin Pass above effective floor (85/100 = 85.0%)
      2. Above nominal floor (87/100 = 87.0%) Pass
      3. Noise-window Fail at nominal (85/100 Fails nominal)
      4. Below-effective Fail incl. HumanEval-canonical 139/164 = 84.756%
      5. Monotonicity sweep correct=0..=164 at effective
      6. Div-safety (total=0) + sanity (correct>total) → Fail
      7. Non-finite threshold (NaN, ±∞) → Fail conservatively
      8. Tolerance-bounded provenance pin on all three constants
         (86.0 − 1.2 in f32 yields ~84.79999924, not exact 84.80).
  - `ship_blocking: true`, `discharge_status: PARTIAL_ALGORITHM_LEVEL`,
    `full_discharge_blocks_on: live apr eval --benchmark humaneval ...`
    on RTX 4090; 6 named counter_example_classes.

crates/aprender-core/src/metrics/ship_005.rs (NEW, 305 lines):
  - Three-constant design unique to MODEL-1 (SHIP-007/018 had one).
  - `#[must_use] pub fn verdict_from_pass_at_1(...)` returns
    `Ship005Verdict::Fail` conservatively on: total=0 (div guard),
    correct>total (sanity), !threshold.is_finite() (NaN/±∞).
  - `falsify_ship_005_humaneval_pass_at_1_threshold_logic` — 1 passing.

Spec `docs/specifications/aprender-train/ship-two-models-spec.md`
  v2.26.0 → v2.27.0 annotates AC-SHIP1-005 + FALSIFY-SHIP-005 rows
  `**(PARTIAL_ALGORITHM_LEVEL v2.27.0)**` and appends amendment entry
  noting 11 PARTIAL + 3 DISCHARGED across both models, MODEL-1 5/10.

Authored self-contained because SHIP-018 PR #1004 and SHIP-007 PR
#1019 are not yet on main. Once they land, the two (or three)
`verdict_from_pass_at_1_*` fns should be dedup'd into a single
parameterized helper.

Full discharge blocks on: live `apr eval --benchmark humaneval
paiml/qwen2.5-coder-7b-apache-q4k-v1 --json` on RTX 4090 with
--features cuda; median pass@1 across 3 seed=0 runs ≥ 86.00 (or
≥ 84.80 under the 1.2 pp noise allowance).

Tests:
  cargo test -p aprender-core --lib \
    falsify_ship_005_humaneval_pass_at_1_threshold_logic
Contract:
  cargo run --quiet -p aprender-contracts-cli --bin pv -- validate \
    contracts/qwen2-e2e-verification-v1.yaml

Supersedes #1015 (stacked-branch original).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Previous run 24806028080 workspace-test stuck at 37+min on lib-tests step
(vs typical 19min). Canceled. Re-triggering on fresh runner.

Tracking: infra issue #1020 second incidence.