i18n: wrap hardcoded UI strings for Chinese localization

- Wrap remaining hardcoded UI labels and buttons with tr()/tl!() calls
- Add missing Simplified and Traditional Chinese translations
- Add entries to other language catalogs for consistency

crates/ui-egui/src/i18n/cs.tsv

@@ -660,3 +660,6 @@
 	Video	Video
 	De-Interlace…	Odstranit prokládání…
 	NTSC Colors	Barvy NTSC
+	RGB:	RGB:
+	CMYK:	CMYK:
+	CMYK	CMYK

crates/ui-egui/src/i18n/es.tsv

@@ -3929,3 +3929,5 @@ axis	Both	Ambos
 	Duplication	Duplicación
 	Interpolation	Interpolación
 @msg	Imported library {name}	Biblioteca {name} importada
+	RGB:	RGB:
+	CMYK:	CMYK:

crates/ui-egui/src/i18n/fr.tsv

@@ -3940,3 +3940,5 @@ axis	Both	Les deux
 	Duplication	Duplication
 	Interpolation	Interpolation
 @msg	Imported library {name}	Bibliothèque {name} importée
+	RGB:	RGB:
+	CMYK:	CMYK:

crates/ui-egui/src/i18n/it.tsv

@@ -3929,3 +3929,5 @@ axis	Both	Entrambi
 	Duplication	Duplicazione
 	Interpolation	Interpolazione
 @msg	Imported library {name}	Libreria {name} importata
+	RGB:	RGB:
+	CMYK:	CMYK:

crates/ui-egui/src/i18n/ja.tsv

@@ -3921,3 +3921,5 @@ theme	Appearance	外観
 	Duplication	複製
 	Interpolation	補間
 @msg	Imported library {name}	ライブラリ {name} を読み込みました
+	RGB:	RGB:
+	CMYK:	CMYK:

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

@@ -254,6 +254,13 @@ pub fn lang_from_tag(tag: &str) -> Option<Lang> {
     cands.iter().find_map(|c| Lang::from_code(c))
 }
 
+/// True when `tag` names the generic `C` / `POSIX` locale (or a variant like `C.UTF-8`), which on
+/// macOS means "no particular language" rather than English: the system language list decides.
+fn is_c_locale(tag: &str) -> bool {
+    let base = tag.split(['.', '@']).next().unwrap_or("").to_ascii_lowercase();
+    matches!(base.as_str(), "c" | "posix")
+}
+
 /// Work out the system language on a background thread, so the first frame doesn't wait for the
 /// locale probe (which runs `reg.exe` on Windows and `defaults` on macOS). Call it at startup; a
 /// frame that needs the language before the probe finishes waits for it. A no-op on wasm.
@@ -295,6 +302,11 @@ fn detect_system_lang() -> Lang {
     // variables. `LANGUAGE` is a colon-separated priority list.
     for var in ["VECTORCRAFT_LOCALE", "LC_ALL", "LC_MESSAGES", "LANG", "LANGUAGE"] {
         let Some(v) = std::env::var(var).ok().filter(|v| !v.is_empty()) else { continue };
+        // `C` / `POSIX` (and variants like `C.UTF-8`, `POSIX.UTF-8`) mean "no particular locale":
+        // don't force English, fall through to the OS preferred-languages list below.
+        if v.split(':').all(is_c_locale) {
+            continue;
+        }
         if let Some(l) = v.split(':').find_map(lang_from_tag) {
             return l;
         }

crates/ui-egui/src/i18n/pt-br.tsv

@@ -2721,3 +2721,5 @@
 	Video	Vídeo
 	De-Interlace…	Desentrelaçar…
 	NTSC Colors	Cores NTSC
+	RGB:	RGB:
+	CMYK:	CMYK:

crates/ui-egui/src/i18n/ru.tsv

@@ -3927,3 +3927,5 @@ axis	Both	Оба
 	Duplication	Дублированием
 	Interpolation	Интерполяцией
 @msg	Imported library {name}	Импортирована библиотека {name}
+	RGB:	RGB:
+	CMYK:	CMYK:

crates/ui-egui/src/i18n/uk.tsv

@@ -3912,3 +3912,5 @@ axis	Both	Обидві
 	Duplication	Дублюванням
 	Interpolation	Інтерполяцією
 @msg	Imported library {name}	Імпортовано бібліотеку {name}
+	RGB:	RGB:
+	CMYK:	CMYK:

crates/ui-egui/src/i18n/zh-hant.tsv

@@ -3340,3 +3340,5 @@ axis	Both	兩者
 	Even Fields	偶數圖場
 	Duplication	複製
 	Interpolation	內插
+	RGB:	RGB：
+	CMYK:	CMYK：

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

@@ -424,7 +424,7 @@ pub(crate) fn label_or_name(s: &str, built_in: bool) -> &str {
 /// command feeds); returns the one clicked, for the caller to apply.
 pub(crate) fn recent_colors_row(app: &VectorcraftApp, ui: &mut Ui) -> Option<Color> {
     let t = Tokens::get(ui.ctx());
-    crate::widgets::subheader(ui, "Recent Colors");
+    crate::widgets::subheader(ui, tl!("Recent Colors"));
     let (r, _) = ui.allocate_exact_size(vec2(ui.available_width(), 22.0), Sense::hover());
     ui.painter().rect_stroke(r, 0.0, egui::Stroke::new(1.0, t.input_border), egui::StrokeKind::Inside);
     let mut chosen = None;

crates/ui-egui/src/panels/separations.rs

@@ -50,7 +50,7 @@ fn plates_section(app: &mut VectorcraftApp, ui: &mut Ui) {
                     run(app, "view.separationsPreview", json!({"plates": plates.iter().map(|p| p.name.clone()).collect::<Vec<_>>()}));
                 }
             });
-            ui.label(egui::RichText::new("CMYK").size(12.0).color(if on { t.text } else { t.text_dim }));
+            ui.label(egui::RichText::new(tl!("CMYK")).size(12.0).color(if on { t.text } else { t.text_dim }));
         });
         for p in &plates {
             ui.horizontal(|ui| {
@@ -86,13 +86,13 @@ fn settings_section(app: &mut VectorcraftApp, ui: &mut Ui) {
     let st = cms::active_settings();
     widgets::section_header(ui, tl!("Color Settings"));
     ui.horizontal(|ui| {
-        ui.label("RGB:");
+        ui.label(tl!("RGB:"));
         if let Some(n) = profile_dropdown(ui, "cms-rgb", &st.rgb, ProfileKind::Rgb, None) {
             run(app, "edit.colorSettings", json!({"rgb": n}));
         }
     });
     ui.horizontal(|ui| {
-        ui.label("CMYK:");
+        ui.label(tl!("CMYK:"));
         if let Some(n) = profile_dropdown(ui, "cms-cmyk", &st.cmyk, ProfileKind::Cmyk, None) {
             run(app, "edit.colorSettings", json!({"cmyk": n}));
         }

crates/ui-egui/src/theme.rs

@@ -255,9 +255,53 @@ pub fn install_fonts(ctx: &egui::Context) {
     mono.extend(fallback);
     fonts.families.insert(FontFamily::Name(FONT_MONO.into()), mono);
     add_craft_fonts(&mut fonts);
+    // System CJK fallback (PingFang / Heiti / Noto…) when craft-fonts are absent.
+    if let Some((name, data)) = system_cjk_font() {
+        fonts.font_data.insert(name.clone(), Arc::new(data));
+        for stack in fonts.families.values_mut() {
+            stack.push(name.clone());
+        }
+    }
     ctx.set_fonts(fonts);
 }
 
+/// A CJK font already installed on the system, as a last-resort fallback.
+fn system_cjk_font() -> Option<(String, FontData)> {
+    #[cfg(not(target_arch = "wasm32"))]
+    {
+        let paths: &[&str] = if cfg!(target_os = "macos") {
+            &[
+                "/System/Library/Fonts/PingFang.ttc",
+                "/System/Library/Fonts/STHeiti Medium.ttc",
+                "/System/Library/Fonts/STHeiti Light.ttc",
+                "/System/Library/Fonts/Hiragino Sans GB.ttc",
+                "/System/Library/Fonts/Supplemental/Songti.ttc",
+                "/Library/Fonts/Arial Unicode.ttf",
+            ]
+        } else if cfg!(target_os = "windows") {
+            &[r"C:\Windows\Fonts\msyh.ttc", r"C:\Windows\Fonts\simhei.ttf", r"C:\Windows\Fonts\simsun.ttc"]
+        } else {
+            &[
+                "/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc",
+                "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc",
+                "/usr/share/fonts/truetype/wqy/wqy-zenhei.ttc",
+            ]
+        };
+        for path in paths {
+            if let Ok(bytes) = std::fs::read(path) {
+                let mut data = FontData::from_owned(bytes);
+                data.index = 0;
+                return Some(("system-cjk".to_string(), data));
+            }
+        }
+        None
+    }
+    #[cfg(target_arch = "wasm32")]
+    {
+        None
+    }
+}
+
 /// The egui name of a craft-fonts face.
 pub(crate) fn craft_font_name(f: &vectorcraft_text::CraftFont) -> String {
     format!("craft-fonts {} {}", f.family, f.style)

crates/ui-egui/src/widgets.rs

@@ -598,10 +598,10 @@ pub fn fill_stroke_proxy(ui: &mut Ui, fill: &Paint, stroke: &Paint, mixed: (bool
         None
     };
     ProxyClicks {
-        fill: fill_resp.on_hover_text("Fill (X), double-click for the Color Picker").clicked(),
-        stroke: stroke_resp.on_hover_text("Stroke (X), double-click for the Color Picker").clicked(),
-        swap: swap.on_hover_text("Swap Fill and Stroke (Shift+X)").clicked(),
-        default: def.on_hover_text("Default Fill and Stroke (D)").clicked(),
+        fill: fill_resp.on_hover_text(tl!("Fill (X), double-click for the Color Picker")).clicked(),
+        stroke: stroke_resp.on_hover_text(tl!("Stroke (X), double-click for the Color Picker")).clicked(),
+        swap: swap.on_hover_text(tl!("Swap Fill and Stroke (Shift+X)")).clicked(),
+        default: def.on_hover_text(tl!("Default Fill and Stroke (D)")).clicked(),
         pick,
     }
 }
@@ -1668,7 +1668,7 @@ pub fn harmony_wheel(ui: &mut Ui, id: &str, size: f32, colors: &[Color], base: O
     ui.add_space(6.0);
     ui.horizontal(|ui| {
         ui.add_space(((ui.available_width() - size - 76.0) / 2.0).max(0.0));
-        ui.add_sized([70.0, 22.0], egui::Label::new(egui::RichText::new("Brightness").color(t.text_dim)));
+        ui.add_sized([70.0, 22.0], egui::Label::new(egui::RichText::new(tl!("Brightness")).color(t.text_dim)));
         if let (Some(b), Some([h, s, _])) = (base, base_hsb)
             && let (Some(nv), _) = color_slider(ui, (id, "brightness"), v, size, &|x| crate::panels::c32(&Color::from_hsb(h, s, x)))
         {