make isort no longer reaches pcapkit/const/reg/apptype/__init__.py after the #754 split

[JarryShaw]

Describe the bug

make isort sorts __init__.py under pcapkit/const/ and pcapkit/vendor/ through a
two-level glob, pcapkit/{const,vendor}/*/*.py (Makefile:126). Since #754 split AppType
into a package, pcapkit/const/reg/apptype/__init__.py sits three levels down and that glob no
longer reaches it — and Makefile:125, which does recurse the whole tree, passes
--skip-glob '**/__init__.py'. So the file is sorted by no make isort line.

Reproduction

$ python -c "import glob; g=glob.glob('pcapkit/const/*/*.py')+glob.glob('pcapkit/vendor/*/*.py'); \
print(len(g), [p for p in g if 'apptype' in p])"
264 []

$ ls pcapkit/const/reg/apptype/
__init__.py  apptype.py  dccp.py  sctp.py  tcp.py  udp.py

Expected behavior

Every __init__.py under pcapkit/const/ and pcapkit/vendor/ is reached by make isort,
regardless of nesting depth.

Additional context

The file is isort-clean today, so nothing is currently broken — this is a latent hole that
would let it drift silently. pcapkit/const/reg/apptype/ is the only package of this shape at
present, so the blast radius is one file, but the glob will keep missing any future split.

Fix is either a recursive glob (pcapkit/{const,vendor}/**/*.py) or dropping the separate line
and narrowing :125's --skip-glob instead. Found while fixing #757/#753; related to #761,
which adds tests/project/test_isort_clean.py and inherits the same blind spot if it reuses the
Makefile's globs verbatim.