staging CI green-up: P-1 apply-slot wedge under JSPI, popup P-4 regression, ysync double-seed header, spec fixes

- P-1 (findings-p.spec P-1c red on CI + locally): a JS exception thrown from a
  window.kicadCollab wire callback does NOT reach the C++ catch(...) — under
  JSPI it REJECTS the promising coroutine entry, slot.done never flips and the
  apply slot is busy for the page's life. Three layers: libcontext flags the
  rejected record dead (kicad → d0afbc4bd3),
  drainApplies() reaps a !done && !CanResume() body, and every EM_ASM
  window.kicadCollab.onX(...) call is try/catch-guarded (collab_common.h,
  kicad_editor/eeschema/pl_editor embind).
- popup.spec 'dismisses on outside click': wx P-4 SetFocus delegation excluded
  for wxPopupWindow (wxwidgets → a7436d1052).
- ysync-two-tab concurrent seed: repairLayoutY + seedNonce retraction deleted
  both headers (pcbjam-shared → 8dabf2e).
- dark-mode.spec: stale light-mode reference (pre wx fa46f1822c DOM
  re-projection) replaced with the CI chromium render.
- items-wire-batch-loss.spec: precondition obsolete after P-5 — poisoned entry
  is now synthetic, plus a P-5 contract assertion (field blob == '').
- presence-ghost-peer.spec: skip early when no /parties/ socket (CI web e2e
  runs the BroadcastChannel provider); findings-p1.spec: polled click-select
  precondition.

Local: kicad-chromium findings/presence/ysync/collab 59/59, popup 7/7,
dark-mode 1/1, pcbjam-shared vitest 249/249.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LvvARNMxQrq17vogn3REMU

web/pcbjam-shared

@@ -1 +1 @@
-Subproject commit ff8835ccc173b5ff9b35ade95440793244ef27b4
+Subproject commit 8dabf2e8232f259a52eb2e2382c6a5a866bcbb1d