Let the benchmark fixture be any size, so the scaling question can be asked

count is now a parameter: ./tools/benchmark-fixture.sh --count 20000 builds the folder the performance doc has been promising 5000 and 20000-file numbers for. The script validates the argument rather than quietly building the default folder, which is the failure mode that would otherwise waste a run. Verified with 1500 files and then removed.

tools/benchmark-fixture.sh

@@ -19,6 +19,18 @@ package=de.softwareapp_hb.filemanager
 directory=/sdcard/AABenchmark
 count=1000
 
+# The size is a knob because the interesting question is how the browser scales: 1 000 files is what the
+# benchmark uses by default, and 5 000 or 20 000 is the same run with a bigger folder:
+#
+#   ./tools/benchmark-fixture.sh --count 20000
+if [ "${1:-}" = "--count" ]; then
+    count=${2:?"--count needs a number"}
+    case "$count" in
+        ''|*[!0-9]*) echo "benchmark-fixture: --count needs a number, not '$count'" >&2; exit 2 ;;
+    esac
+    shift 2
+fi
+
 case "${1:-create}" in
     --remove)
         adb shell "rm -rf $directory"