test(asyncify): red-green race harness + ablation flags, unwind-catch shim, spec tightening, decisions docs

The asyncify single-slot work, executed red-green (full ledger:
docs/features/asyncify-arbiter/redgreen.md; decisions record:
docs/features/async/07-decisions-and-outcome.md):

- tests/apps/standalone/asyncify-races/ + tests/asyncify/ + dedicated
  playwright config: 8 scenarios reproducing the KiCad asyncify failure
  family with the kicad-faithful startup topology (pre-park fiber swap →
  park throw through the live trampoline). Built in 3 variants; the
  SHIM_DISABLE_TRAMPOLINE_HEAL / SHIM_DISABLE_HANDLESLEEP ablation builds
  keep the historical hang and index-out-of-bounds crash reproducible
  forever (mutation-style pins for the existing shims).
- scripts/common/shims/handlesleep.js: catch the "unwind" park sentinel
  in the wakeUp path — when main's last pre-park suspension was a sleep,
  the main-loop park throw escaped through that sleep's promise reaction
  as an uncaught rejection (the calculator/gerbview console errors).
- scripts/common/inject-dyncall-shims.sh: SHIM_DISABLE_* ablation knobs.
- Spec tightening (the acceptance bar): 'uncaught exception: unwind'
  tolerance DELETED from pcbnew/eeschema specs; load-pcb gained a hard
  clean-console gate over 5 asyncify corruption signatures.
- wxwidgets pointer bump: modal LIFO resolvers, pump resolve-on-error,
  sync clipboard IsSupported (014f67e6c1).

Final state: asyncify suite 7/7, wx e2e 291/292 (1 skip), KiCad e2e 40
passed / 2 skipped with ZERO corruption signatures in any log across all
six apps.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/features/asyncify-arbiter/baseline.md

@@ -0,0 +1,59 @@
+# Baseline — pre-fix state (2026-06-12)
+
+Artifacts under test for the KiCad baseline run:
+- `output/pcbnew.js` + `output/eeschema.js` from `docker/build.sh pcbnew,eeschema`
+  started 14:20 (container rsyncs source at start → consistently PRE-fix wx:
+  async clipboard IsSupported, single-slot `Module._endModal`, silently-stalling
+  modal/nested pumps). Shims as of the same moment: §3c trampoline heal INCLUDED,
+  handlesleep.js WITHOUT the wakeUp "unwind" catch.
+- This is the first build of these apps since `18a9de0` (trampoline heal) —
+  the previously deployed artifacts predated it, which is why the load-pcb UI
+  froze post-load in the user's earlier runs.
+
+## Standalone harness reds recorded pre-fix
+
+See `redgreen.md` — 3 reds (sleep-park unwind rejection; modal_in_modal_in_modal
+stall; nested pump-error stall) + 2 ablation pins reproducing the historical
+hang and clobber crash.
+
+## KiCad e2e baseline run (npm run test:kicad, firefox)
+
+- Full playwright summary: **40 passed, 2 skipped, 0 failed, 0 flaky** (1.5 m).
+  Green-at-baseline because this is the first deployed build containing the
+  §3c trampoline heal (`18a9de0`) — the freeze-after-load the user saw came
+  from pre-heal artifacts.
+- Failures classified pre-existing/unrelated: none (2 skips are by design).
+- Asyncify errors present in logs DESPITE passing (the "before" evidence the
+  post-fix rebuild must eliminate, currently tolerated by spec filters):
+  - `logs/kicad/load-pcb/...pic-programmer....errors.log`:
+    `RuntimeError: index out of bounds` — the clipboard 2 s `IsSupported`
+    sleep clobber (wx fix: sync IsSupported).
+  - `logs/kicad/calculator/...loads-calculator-frame.errors.log` and
+    `...switch-to-color-code-panel.errors.log`: `uncaught exception: unwind` —
+    the park throw escaping through a sleep's wakeUp (shim fix: handlesleep.js
+    unwind catch).
+
+## wxWidgets e2e regression (against the FIXED wx — the regression gate for
+## the dialog.cpp/evtloop.cpp/clipbrd.cpp changes)
+
+- Coroutine suite (firefox): 13 passed, 0 failed (49.8 s)
+- Asyncify races suite (firefox): 7 passed, 0 failed (18.8 s)
+- Full wx e2e (bundled chromium): **291 passed, 1 skipped, 0 failed, 0 flaky** (1.6 m)
+
+No regressions from the modal LIFO resolver stack, pump resolve-on-error
+changes, or the sync clipboard IsSupported.
+
+## FINAL verification (post-fix rebuild of ALL 6 apps, tightened specs)
+
+Specs tightened first: `'uncaught exception: unwind'` tolerance DELETED from
+pcbnew.spec.ts/eeschema.spec.ts; load-pcb.spec.ts gained a hard clean-console
+gate over 5 asyncify corruption signatures (before AND after board render).
+
+- `npm run test:kicad` (firefox): **40 passed, 2 skipped, 0 failed, 0 flaky** (1.5 m)
+- Signature sweep over every `tests/logs/kicad/` log
+  (index out of bounds / indirect call to null / uncaught exception: unwind /
+  invalid state / is not a function / Aborted(): **zero matches**
+- `.errors.log` files produced by the run: **zero** (baseline had 5+, including
+  load-pcb's `RuntimeError: index out of bounds` and calculator/gerbview's
+  `uncaught exception: unwind` — all gone)
+- Screenshot baselines: unchanged (no rendering impact).