fix(ci): wait for asynchronous NSIS uninstaller surface cleanup

The installer smoke asserted a clean registry and shortcut surface
immediately after the silent uninstall returned and the installation
directory disappeared. NSIS uninstallers run detached through a
temporary copy, so shortcut and registry removal completes after the
invoked process exits, and on current runner images the immediate check
raced that cleanup and failed with leftover HKCU keys and shortcuts.
The smoke now polls the exact same surface assertions until a bounded
deadline, keeping a genuinely dirty uninstall failing, with contract
coverage for the tolerated asynchronous cleanup and the persistent
failure case.

scripts/smoke-test-installer.js

@@ -223,6 +223,19 @@ function verifyInstalledPhase(phase) {
   return uninstallerPath;
 }
 
+async function waitForInstallerSurfaceClean(phases, { keyExists, pathExists = fs.existsSync, timeoutMs = 30000, pollIntervalMs = 250 }) {
+  const deadline = Date.now() + timeoutMs;
+  for (;;) {
+    try {
+      assertInstallerSurfaceClean(phases, { keyExists, pathExists });
+      return;
+    } catch (error) {
+      if (Date.now() >= deadline) throw error;
+      await new Promise((resolve) => setTimeout(resolve, pollIntervalMs));
+    }
+  }
+}
+
 async function waitForPathRemoval(targetPath, timeoutMs = 10000) {
   const deadline = Date.now() + timeoutMs;
   while (fs.existsSync(targetPath)) {
@@ -274,7 +287,7 @@ async function main() {
       if (!await waitForPathRemoval(phase.installationDirectory, 30000)) {
         throw new Error(`Silent uninstall left the installation directory behind: ${phase.installationDirectory}`);
       }
-      assertCleanInstallerSmokeSurface(phases);
+      await waitForInstallerSurfaceClean(phases, { keyExists: registryKeyExists });
       results.push({
         flag: phase.flag,
         hive: phase.hive,
@@ -314,5 +327,6 @@ module.exports = {
   assertShortcutDetails,
   createInstallerPhases,
   readShortcutDetails,
-  registryKeys
+  registryKeys,
+  waitForInstallerSurfaceClean
 };