fix(picker): cascade thread DPI contexts and harden the round-three review points

- setThreadDpiAwareness checks SetThreadDpiAwarenessContext's return value
  and cascades per-monitor-v2 -> per-monitor -> system-aware; DPI stays a
  deliberate cosmetic best-effort - a host accepting none (or lacking the
  API, pre-1607) still gets the modern dialog instead of a downgrade to the
  legacy fallback chain over a cosmetic concern.
- The mocked-koffi world now uses a distinctive 4-byte pointer width and
  rejects mis-sized out-buffers and mis-divided vtable offsets, so a
  regression to hardcoded 8s fails the suite (the ia32 bug class).
- A keyless built-worker e2e guard loads lib/worker.cjs under plain
  worker_threads on POSIX (the workflow-workerthread shape).
- The 'loaded lazily' module claims are reworded to attribute laziness to
  the dynamic import('koffi') calls, and the discarded close-attempt
  rejection is named at its catch.

packages/host/directory-picker-native/src/win32-dialog.ts

@@ -83,7 +83,9 @@ export async function pickWin32Directory(
 
     const postClose = (): void => {
       // Before `showing` there is no window to close; the budget below still
-      // runs so a worker that never reports cannot dangle the pick.
+      // runs so a worker that never reports cannot dangle the pick. A
+      // rejected close attempt (EnumThreadWindows/PostMessageW refusing) is
+      // discarded: the interval retries it and terminate is the backstop.
       if (dialogThreadId !== undefined) void closeWindows(dialogThreadId).catch(() => undefined)
     }