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>

tests/apps/Makefile.wasm

@@ -97,6 +97,12 @@ COROUTINE_BASE_LDFLAGS = -sALLOW_MEMORY_GROWTH -sERROR_ON_UNDEFINED_SYMBOLS=0 \
                -sASYNCIFY_IMPORTS=['startModal','js_writeTextToClipboard','js_readTextFromClipboard','js_clipboardHasText','js_clearClipboard','js_enumerateFonts','emscripten_fiber_swap']
 LDFLAGS_COROUTINE = $(DEBUG_LDFLAGS) $(COROUTINE_BASE_LDFLAGS) $(WX_LDFLAGS_NOGL)
 
+# The asyncify-races harness must match PRODUCTION asyncify semantics: the KiCad
+# apps ship with assertions off and rely on the shim layer, while emscripten's
+# debug assert ("We cannot start an async operation when one is already flight")
+# forbids the very multi-parked-sleep states the harness exists to exercise.
+LDFLAGS_RACES = $(DEBUG_LDFLAGS) $(COROUTINE_BASE_LDFLAGS) -sASSERTIONS=0 $(WX_LDFLAGS_NOGL)
+
 JS = $(TOOLS_ROOT)/wx.js
 HTML = $(TOOLS_ROOT)/template.html
 
@@ -157,6 +163,9 @@ all: minimal_test.html \
      $(S)/retinascale/retinascale_test.html \
      $(S)/coroutine/coroutine_test.html \
      $(S)/coroutine-nested/nested_test.html \
+     $(S)/asyncify-races/races_test.html \
+     $(S)/asyncify-races/races_test_noheal.html \
+     $(S)/asyncify-races/races_test_nosleepfix.html \
      $(S)/coroutine-pthread/coroutine_test_wxpt.html \
      $(S)/coroutine-pthread/embind_repro.html \
      $(S)/coroutine-pthread/gl_repro.html \
@@ -487,6 +496,25 @@ $(S)/coroutine-nested/nested_test.html: $(S)/coroutine-nested/nested_test.o $(S)
 	$(CXX) $^ $(LDFLAGS_COROUTINE) --pre-js $(JS) --shell-file $(HTML) -o $@
 	../../scripts/common/inject-dyncall-shims.sh $(basename $@).js
 
+# Asyncify race-condition red-green harness (tests/asyncify/). Three variants of
+# the same app: full shims, trampoline-heal ablated, handleSleep-fix ablated.
+# The ablated builds keep the historical bugs reproducible (red) so the shim
+# fixes stay pinned by tests. Same .o, three link+inject passes.
+$(S)/asyncify-races/races_test.o: $(S)/asyncify-races/races_test.cpp $(S)/coroutine/kicad_coroutine_harness.h
+	$(CXX) -c $(CXXFLAGS) -I$(KICAD_ROOT)/thirdparty/libcontext -I$(S)/coroutine $< -o $@
+
+$(S)/asyncify-races/races_test.html: $(S)/asyncify-races/races_test.o $(S)/coroutine/libcontext.o $(WX_CORE_LIB)
+	$(CXX) $^ $(LDFLAGS_RACES) --pre-js $(JS) --shell-file $(HTML) -o $@
+	../../scripts/common/inject-dyncall-shims.sh $(basename $@).js
+
+$(S)/asyncify-races/races_test_noheal.html: $(S)/asyncify-races/races_test.o $(S)/coroutine/libcontext.o $(WX_CORE_LIB)
+	$(CXX) $^ $(LDFLAGS_RACES) --pre-js $(JS) --shell-file $(HTML) -o $@
+	SHIM_DISABLE_TRAMPOLINE_HEAL=1 ../../scripts/common/inject-dyncall-shims.sh $(basename $@).js
+
+$(S)/asyncify-races/races_test_nosleepfix.html: $(S)/asyncify-races/races_test.o $(S)/coroutine/libcontext.o $(WX_CORE_LIB)
+	$(CXX) $^ $(LDFLAGS_RACES) --pre-js $(JS) --shell-file $(HTML) -o $@
+	SHIM_DISABLE_HANDLESLEEP=1 ../../scripts/common/inject-dyncall-shims.sh $(basename $@).js
+
 # Convenience targets
 menu: $(S)/menu/menu_test.html
 clipboard: $(S)/clipboard/clipboard_test.html
@@ -541,6 +569,7 @@ $(S)/retinascale/retinascale_test.html: $(S)/retinascale/retinascale_test.o $(WX
 retinascale: $(S)/retinascale/retinascale_test.html
 coroutine: $(S)/coroutine/coroutine_test.html
 coroutine-nested: $(S)/coroutine-nested/nested_test.html
+asyncify-races: $(S)/asyncify-races/races_test.html $(S)/asyncify-races/races_test_noheal.html $(S)/asyncify-races/races_test_nosleepfix.html
 
 # Only delete generated app files (*_test*, *_repro*) — a bare $(S)/*/*.js would
 # also delete checked-in sources like coroutine-pthread/worker_dom_stub.js.
@@ -550,7 +579,7 @@ clean:
 	rm -f $(S)/*/*_test*.html $(S)/*/*_test*.js $(S)/*/*_test*.wasm
 	rm -f $(S)/*/*_repro*.html $(S)/*/*_repro*.js $(S)/*/*_repro*.wasm
 
-.PHONY: all clean menu clipboard filedialog layout aui toolbar grid dialog timer tree dataview htmlwin stc print dnd propgrid pickers collapsible listctrl infobar dataviewvirtual auinotebook wizard gridedit calendar gridrenderers printpreview bitmapbuttons specialized validators ownerdrawn popup xml wasmedge fontenum textdecor bitmask regions maximize earlysize threadpool logerror retinascale coroutine coroutine-nested
+.PHONY: all clean menu clipboard filedialog layout aui toolbar grid dialog timer tree dataview htmlwin stc print dnd propgrid pickers collapsible listctrl infobar dataviewvirtual auinotebook wizard gridedit calendar gridrenderers printpreview bitmapbuttons specialized validators ownerdrawn popup xml wasmedge fontenum textdecor bitmask regions maximize earlysize threadpool logerror retinascale coroutine coroutine-nested asyncify-races
 
 # === Coroutine pthread variant — reproduces the KiCad Asyncify-fiber x pthreads crash ===
 # Same modal-free harness as `coroutine`, but compiled/linked with pthreads to match