en.json and de.json each defined the checks object twice; JSON silently
kept the second block's values, so the first block's friendlier titles/hints
(e.g. "Permission Mode" over the raw "--permission-mode auto support" flag)
were dead text. Merged into one block per key, keeping the friendlier title
and the more actionable hint.
Added a Utf8JsonReader-based duplicate-top-level-key test, since
JsonDocument accepts duplicates without error and the existing parity test
can't see this failure mode either.
LocaleStore.Load silently skips a *.json that fails to parse, so a broken
de.json left store.Available with only "en" and the parity loop compared
English against itself, always green. Add two guards before the loop:
loaded-locale count must match the number of *.json files in the folder,
and "de" must be present via TryGet, both with failure messages naming the
missing file. Also independently JsonDocument.Parse every *.json so a
syntax error surfaces as a syntax error with the file name, not as
"locale missing". LocaleStore's catch-and-skip is untouched -- a broken
translation must still not crash the app at runtime.
mika kuns