`양. 지훈` splits the given name in half

[derek73]

parse("양 지훈")    # given 지훈, family 양            correct
parse("양. 지훈")   # given 양., middle 지, family 훈   wrong

지훈 is one given name. The second form cuts it in two.

This is exactly the harm _script_segment._is_post_nominal's docstring names — "지 is a listed surname, so 양 지훈 … would have its own given name split in half" — and the guard that prevents it is standing right there, unable to fire.

Why it cannot fire

_split_surname_site picks its site by effective_script(...) in scripts. effective_script("양.") returns None, because the trailing period defeats the wholly-one-script test, so the site scan steps straight past 양. and lands on the given name. The guard downstream never gets asked.

effective_script("양")   -> hangul
effective_script("양.")  -> None
is_suffix_strict("양.")  -> True     (since #320)

That last line is what makes this newly visible rather than newly broken: #320 made _is_post_nominal("양.") return True, so the predicate now says "this is a post-nominal" while the caller structurally cannot ask it. Output is identical on master, so this is not a regression — but the branch created the half-state that makes the gap legible.

양 and 군 are the shipped vocabulary's designated risk class (config/suffixes.py singles them out — 양 is a top-tier Korean surname), which is why this shape is worth fixing rather than filing as a curiosity.

Two candidate fixes, and the choice matters

• Teach the surname site to consult is_suffix_strict alongside effective_script.
• Make effective_script tolerant of a trailing period.

The second is broader and would interact with the normalization question in #322.

Found while reviewing #320 (PR #321).