POSIX bracket ranges like a-z follow the active collation order; under GNU
grep with tr_TR.UTF-8 the range excludes the ASCII letter i, so every key
containing i (skill_prefix, explain_level, ...) was rejected as invalid.
Pin both get/set validators to LC_ALL=C, with a source-level tripwire test
since macOS BSD grep doesn't reproduce the bug.
Closes#2494.
Contributed by @Math1987 (PR #2506).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Garry Tan