- File picker (app.filepicker.pas): add otSYMLINK to directory case in
fp_collect_cb so symlinks like /sys appear as navigable directories
- VFS: add RemoveVirtualTree() to recursively free vdir/symlink trees
- VFS UnitTest: clean up /utest_vfs tree after all tests
- STORTEST: clean up /st_test tree after tests, fix listing leak in
cmd_stortest (GetDirectoryListingFrom result was never freed)
- Boot mount: auto-mount boot drive at /boot via mountVolume() instead
of symlink; remove /boot and /cfg from init() vdirs
- mount.asr: remove boot line (now only 'mnt {device}/sys /sys')