## Summary

PR #460 added a selection character-count feature to the word-count
widget and introduced three new plural string keys, but only in
`en.lproj`. In any other locale, `NSLocalizedString` returns the **key
name** (not an English fallback) when the key is absent, so
`JJPluralForm` can't parse it and the widget shows **"ERR"** when text
is selected. Reported by rcuisnier in French during rc.1 testing.

This adds the three keys to all 25 non-English locales:

- `WORDS_SELECTED_PLURAL_STRING`
- `CHARACTERS_SELECTED_PLURAL_STRING`
- `CHARACTERS_NO_SPACES_SELECTED_PLURAL_STRING`

## Approach

Each locale's translation was built from its **existing** base plural
vocabulary (`WORDS_PLURAL_STRING`, etc.) plus the word for "selected,"
with grammatical agreement matched per language — gender/number in
Romance, Slavic, Hebrew, Arabic, Icelandic; case agreement in Finnish;
invariant participles where appropriate (German, Dutch, Turkish, Hindi,
CJK). The two-form `"%@ singular;%@ plural"` structure and
`JJ_PLURAL_FORM_RULE = "1"` convention are preserved.

A few forms were refined after review:
- **Japanese** uses the state form `選択中` ("currently selected") rather
than a verb reading as a command.
- **Arabic / Hebrew** place the participle adjacent to the noun; Hebrew
uses `מסומן` ("marked/selected") with correct final-vs-medial nun across
gender/number.

## Verification

- `grep -L` confirms all 25 non-English files now contain the keys; none
missing.
- `en.lproj` unchanged; no existing keys altered; only the three
additions per file (`25 files changed, 175 insertions`).
- Non-Latin strings decoded to Unicode codepoints to confirm correct
letters and logical byte order (independent of terminal shaping/BiDi).

Related to #452