i18n: add French (fr) UI translation (#410)

* i18n: add French (fr) UI translation

A complete French catalog (menus, dialogs, panels, plurals), registered with its
plural rule (0 and 1 take the singular). Covers the latest commands, Stamp Visible
and Stamp Down included. A test checks the bundled UI fonts carry every French glyph.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

* i18n(fr): translate labels added on main since this PR (from #582 by neko233-com)

Co-Authored-By: neko233-com <242357072+neko233-com@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* i18n(fr): translate the labels added on main since this catalog

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* i18n(fr): Camera Raw scopes and the Patch tool

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>
Co-authored-by: neko233-com <242357072+neko233-com@users.noreply.github.com>

crates/text/src/fonts.rs

@@ -424,6 +424,21 @@ mod tests {
         }
     }
 
+    /// The bundled UI fonts cover French (the `fr` UI language) on their own: every accented
+    /// letter, the ligatures, the guillemets and the no-break space used before `: ; ? !`.
+    #[test]
+    fn bundled_fonts_cover_french() {
+        use skrifa::MetadataProvider;
+        let french = "àâæçéèêëîïôœùûüÿ";
+        let letters: String = french.chars().chain(french.chars().flat_map(char::to_uppercase)).chain("«»\u{a0}’".chars()).collect();
+        for (name, bytes) in super::BUNDLED {
+            let font = skrifa::FontRef::new(bytes).expect("bundled font parses");
+            let cmap = font.charmap();
+            let missing: String = letters.chars().filter(|c| cmap.map(*c).is_none_or(|g| g.to_u32() == 0)).collect();
+            assert!(missing.is_empty(), "{name} lacks French glyphs: {missing:?}");
+        }
+    }
+
     #[test]
     fn missing_font_dirs_are_skipped() {
         let mut files = Vec::new();

crates/ui-egui/src/i18n/mod.rs

@@ -34,7 +34,7 @@ pub struct LangInfo {
     /// Catalog file contents (empty for the built-in English).
     pub source: &'static str,
     /// Plural form index for a count (English: 0 = one, 1 = other; Japanese and Chinese: always 0;
-    /// Czech: 0 = one, 1 = few (2–4), 2 = other). A catalog's `@plural` entries list one form per
+    /// Czech: 0 = one, 1 = few (2–4), 2 = other; French: 0 = one (0 and 1), 1 = other). A catalog's `@plural` entries list one form per
     /// index.
     pub plural: fn(u64) -> usize,
     /// Must the catalog cover every menu string? (checked by the tests)
@@ -69,8 +69,13 @@ fn plural_cs(n: u64) -> usize {
     }
 }
 
+/// French: 0 and 1 take the singular, everything else the plural.
+fn plural_fr(n: u64) -> usize {
+    usize::from(n > 1)
+}
+
 /// The registry. English first: it is the fallback and the source language.
-pub static LANGUAGES: [LangInfo; 7] = [
+pub static LANGUAGES: [LangInfo; 8] = [
     LangInfo { code: "en", name: "English", source: "", plural: plural_one_other, complete_menus: false, catalog: OnceLock::new() },
     LangInfo { code: "ja", name: "日本語", source: include_str!("ja.tsv"), plural: plural_none, complete_menus: true, catalog: OnceLock::new() },
     LangInfo {
@@ -84,6 +89,7 @@ pub static LANGUAGES: [LangInfo; 7] = [
     LangInfo { code: "es", name: "Español", source: include_str!("es.tsv"), plural: plural_one_other, complete_menus: true, catalog: OnceLock::new() },
     LangInfo { code: "ru", name: "Русский", source: include_str!("ru.tsv"), plural: plural_russian, complete_menus: true, catalog: OnceLock::new() },
     LangInfo { code: "cs", name: "Čeština", source: include_str!("cs.tsv"), plural: plural_cs, complete_menus: true, catalog: OnceLock::new() },
+    LangInfo { code: "fr", name: "Français", source: include_str!("fr.tsv"), plural: plural_fr, complete_menus: true, catalog: OnceLock::new() },
 ];
 
 impl LangInfo {
@@ -295,7 +301,7 @@ mod tests {
         assert_eq!(lang_from_tag("POSIX"), Some(Lang::EN));
         assert_eq!(lang_from_tag("cs_CZ.UTF-8"), Some(CS()));
         assert_eq!(lang_from_tag("cs-CZ"), Some(CS()));
-        assert_eq!(lang_from_tag("fr_FR"), None);
+        assert_eq!(lang_from_tag("de_DE"), None);
         // Traditional Chinese: by region, by script, and with a region after the script.
         assert_eq!(lang_from_tag("zh_TW.UTF-8"), Some(ZH()));
         assert_eq!(lang_from_tag("zh-TW"), Some(ZH()));
@@ -324,7 +330,7 @@ mod tests {
     #[test]
     fn macos_language_list_is_parsed() {
         assert_eq!(first_supported("(\n    \"ja-JP\",\n    \"en-US\"\n)\n"), Some(JA()));
-        assert_eq!(first_supported("(\n    \"fr-FR\",\n    \"en-US\"\n)\n"), Some(Lang::EN));
+        assert_eq!(first_supported("(\n    \"de-DE\",\n    \"en-US\"\n)\n"), Some(Lang::EN));
         assert_eq!(first_supported("(\n    \"zh-Hant-TW\",\n    \"en-US\"\n)\n"), Some(ZH()));
         assert_eq!(first_supported("("), None);
     }
@@ -430,6 +436,22 @@ mod tests {
         assert_eq!(placeholders("a {x} b {y} {"), ["x", "y"]);
     }
 
+    #[test]
+    fn french_resolves_and_pluralises() {
+        let fr = Lang::from_code("fr").expect("fr registered");
+        for tag in ["fr", "fr_FR.UTF-8", "fr-CA", "fr_BE", "fr-CH"] {
+            assert_eq!(lang_from_tag(tag), Some(fr), "{tag}");
+        }
+        assert_eq!(tr(fr, "Layer"), "Calque");
+        assert_eq!(tr_id(fr, "select.all", "All"), "Tout sélectionner", "an id override wins over the plain label");
+        assert_eq!(tr(fr, "All"), "Tout");
+        let forms: Vec<usize> = [0, 1, 2, 5, 100, u64::MAX].into_iter().map(plural_fr).collect();
+        assert_eq!(forms, [0, 0, 1, 1, 1, 1]);
+        assert_eq!(trn(fr, 0, "{n} item", "{n} items"), "0 élément");
+        assert_eq!(trn(fr, 1, "{n} item", "{n} items"), "1 élément");
+        assert_eq!(trn(fr, 3, "{n} item", "{n} items"), "3 éléments");
+    }
+
     #[test]
     fn czech_plural_rule() {
         let forms: Vec<usize> = [0, 1, 2, 3, 4, 5, 11, 12, 21, 22, 100, u64::MAX].into_iter().map(plural_cs).collect();