fix: add -WindowStyle Hidden to powershell command to prevent window flash on Windows (#285)

scripts/installer.nsh

@@ -3,6 +3,73 @@
 ; Install: enables long paths, adds resources\cli to user PATH for openclaw CLI.
 ; Uninstall: removes the PATH entry and optionally deletes user data.
 
+!macro customCheckAppRunning
+  ${GetProcessInfo} 0 $pid $1 $2 $3 $4
+  ${if} $3 != "${APP_EXECUTABLE_FILENAME}"
+    ${if} ${isUpdated}
+      # allow app to exit without explicit kill
+      Sleep 300
+    ${endIf}
+
+    # Instead of launching cmd.exe /c tasklist, use the nsProcess plugin directly for all environments.
+    # This prevents the brief black cmd window from flashing.
+    ${nsProcess::FindProcess} "${APP_EXECUTABLE_FILENAME}" $R0
+
+    ${if} $R0 == 0
+      ${if} ${isUpdated}
+        # allow app to exit without explicit kill
+        Sleep 1000
+        Goto doStopProcess
+      ${endIf}
+      MessageBox MB_OKCANCEL|MB_ICONEXCLAMATION "$(appRunning)" /SD IDOK IDOK doStopProcess
+      Quit
+
+      doStopProcess:
+      DetailPrint `Closing running "${PRODUCT_NAME}"...`
+
+      # Silently kill the process using nsProcess instead of taskkill / cmd.exe
+      ${nsProcess::KillProcess} "${APP_EXECUTABLE_FILENAME}" $R0
+      
+      # to ensure that files are not "in-use"
+      Sleep 300
+
+      # Retry counter
+      StrCpy $R1 0
+
+      loop:
+        IntOp $R1 $R1 + 1
+
+        ${nsProcess::FindProcess} "${APP_EXECUTABLE_FILENAME}" $R0
+        ${if} $R0 == 0
+          # wait to give a chance to exit gracefully
+          Sleep 1000
+          ${nsProcess::KillProcess} "${APP_EXECUTABLE_FILENAME}" $R0
+          
+          ${nsProcess::FindProcess} "${APP_EXECUTABLE_FILENAME}" $R0
+          ${If} $R0 == 0
+            DetailPrint `Waiting for "${PRODUCT_NAME}" to close.`
+            Sleep 2000
+          ${else}
+            Goto not_running
+          ${endIf}
+        ${else}
+          Goto not_running
+        ${endIf}
+
+        # App likely running with elevated permissions.
+        # Ask user to close it manually
+        ${if} $R1 > 1
+          MessageBox MB_RETRYCANCEL|MB_ICONEXCLAMATION "$(appCannotBeClosed)" /SD IDCANCEL IDRETRY loop
+          Quit
+        ${else}
+          Goto loop
+        ${endIf}
+      not_running:
+        nsProcess::Unload
+    ${endIf}
+  ${endIf}
+!macroend
+
 !macro customInstall
   ; Enable Windows long path support (Windows 10 1607+ / Windows 11).
   ; pnpm virtual store paths can exceed the default MAX_PATH limit of 260 chars.