fix(picker): correct crash-isolation and DPI claims, wire the built-worker guard, and tidy round-four nits

The round-four review's v6 pass found three factual gaps and the v5 pass two
nits. Correct them before merge:

- The in-process note claimed a koffi signature mistake is 'contained to
  the worker thread' — worker_threads share the process, so a native access
  violation takes down the whole Node process with no PowerShell fallback.
  State the real blast radius and record the deferred pkg-VFS worker-spawn
  arm in Consequences (both languages, pairing re-recorded).
- The 2026-07-27 picker note claimed unconditional 'per-monitor-v2 DPI';
  PMv2-less hosts (Server 2016 / Win10 1607) cascade to per-monitor or
  system-aware. Say 'the best thread DPI awareness the host accepts'
  (both languages, pairing re-recorded).
- built-worker.e2e.ts was not in any keyless gate (vitest.e2e config is
  not part of the default unit run and builtBinSmokeGate's explicit list
  missed it), so lib/worker.cjs load regressions passed keyless CI. Add it
  to builtBinSmokeGate alongside the workflow-workerthread sibling.
- Remove the dead trailing 'void bindings' in win32-dialog-logic.spec.ts
  and give native-picker.spec.ts the sibling module header it lacked.

.agents/notes/implemented/feature/2026-08-02-win32-in-process-folder-dialog.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-08-02-win32-in-process-folder-dialog.md
-2026-08-02-win32-in-process-folder-dialog.md: 96bc213ea7cddef6223aa3be69e56688dc9c4724
-2026-08-02-win32-in-process-folder-dialog.zh.md: a3dfad2ef73cb28ae8c4c47b6380740aab6de5c3
+2026-08-02-win32-in-process-folder-dialog.md: e18ecd1d2e79ec39a265d3d93913beaa7530e645
+2026-08-02-win32-in-process-folder-dialog.zh.md: f146d61f6378062886db732e6884594d56b3d170