feat(locale): add Fluent translations

Default to the platform language with persisted overrides across native and web builds.

Refs #630

src/ui/command_line.rs

@@ -111,8 +111,8 @@ pub enum EntryKind {
 impl CommandLine {
     pub fn new() -> Self {
         let mut cl = Self::default();
-        cl.push_info("Open CAD Studio ready.");
-        cl.push_info("Type a command or use the ribbon. Open OBJ: INSERT tab.");
+        cl.push_info(&crate::tr!("command-line-ready"));
+        cl.push_info(&crate::tr!("command-line-hint"));
         cl
     }
 
@@ -430,7 +430,7 @@ impl CommandLine {
                 }
             });
         let prompt = container(
-            text("Command:").size(11).style(|theme: &Theme| iced::widget::text::Style {
+            text(crate::tr!("command-line-label")).size(11).style(|theme: &Theme| iced::widget::text::Style {
                 color: Some(theme.palette().success.base.color),
             }),
         )
@@ -467,10 +467,7 @@ impl CommandLine {
                 ..Default::default()
             }
         });
-        let literal_tip = container(
-            text("Literal spaces: Space stays in the line instead of running the command (same as typing a leading '>'). Stays on until toggled off.")
-                .size(11),
-        )
+        let literal_tip = container(text(crate::tr!("command-line-literal-spaces")).size(11))
         .padding([3, 6])
         .style(container::bordered_box);
         let literal_btn = tooltip(literal_btn, literal_tip, tooltip::Position::Top).gap(4);

src/ui/modal.rs

@@ -253,7 +253,7 @@ pub fn backdrop<'a>(
 /// title bar; pass `Vector::ZERO` to keep it centred.
 pub fn modal<'a>(
     base: impl Into<Element<'a, Message>>,
-    title: &'a str,
+    title: impl iced::widget::text::IntoFragment<'a>,
     content: impl Into<Element<'a, Message>>,
     on_close: Message,
     offset: Vector,

src/ui/ribbon/mod.rs

@@ -422,7 +422,7 @@ impl Ribbon {
                 let is_active = i == self.active;
                 let is_contextual = module.id() == "layout";
                 let btn = container(
-                    button(text(module.title()).size(12))
+                    button(text(crate::i18n::ribbon_module_title(module.id(), module.title())).size(12))
                         .on_press(Message::RibbonSelectTab(i))
                         .style(move |theme: &Theme, status| {
                             let palette = theme.palette();

src/ui/window/options.rs

@@ -9,6 +9,7 @@ pub fn view_window<'a>(
     default_save_format: &'a str,
     ui_theme: &'a UiThemeConfig,
     theme_color_inputs: &'a [String; 6],
+    language: crate::i18n::Language,
     sizing: crate::ui::modal::ModalSizing,
 ) -> Element<'a, Message> {
     let selected_format = crate::io::SAVE_FORMAT_OPTIONS
@@ -25,12 +26,12 @@ pub fn view_window<'a>(
 
     let palette = ui_theme.palette.to_iced();
     let colors = [
-        ("Background", palette.background),
-        ("Text", palette.text),
-        ("Primary", palette.primary),
-        ("Success", palette.success),
-        ("Warning", palette.warning),
-        ("Danger", palette.danger),
+        (crate::tr!("options-color-background"), palette.background),
+        (crate::tr!("options-color-text"), palette.text),
+        (crate::tr!("options-color-primary"), palette.primary),
+        (crate::tr!("options-color-success"), palette.success),
+        (crate::tr!("options-color-warning"), palette.warning),
+        (crate::tr!("options-color-danger"), palette.danger),
     ];
 
     let mut color_controls = column![].spacing(8);
@@ -60,16 +61,31 @@ pub fn view_window<'a>(
         );
     }
 
-    let close = button(text("Close").size(12))
+    let close = button(text(crate::tr!("action-close")).size(12))
         .on_press(Message::CloseModal)
         .padding([6, 18])
         .style(button::secondary);
 
     let content = column![
-        text("Open and Save").size(15),
+        text(crate::tr!("options-language-section")).size(15),
         Space::new().height(10),
         row![
-            text("Default save format:").size(12).width(150),
+            text(crate::tr!("options-language-label")).size(12).width(150),
+            iced::widget::pick_list(
+                Some(language),
+                crate::i18n::Language::ALL,
+                |value| value.to_string(),
+            )
+            .on_select(Message::LanguageChanged)
+            .width(sizing.width),
+        ]
+        .spacing(12)
+        .align_y(iced::Center),
+        Space::new().height(22),
+        text(crate::tr!("options-open-save-section")).size(15),
+        Space::new().height(10),
+        row![
+            text(crate::tr!("options-default-save-format-label")).size(12).width(150),
             iced::widget::pick_list(
                 selected_format,
                 crate::io::SAVE_FORMAT_OPTIONS,
@@ -81,16 +97,14 @@ pub fn view_window<'a>(
         .spacing(12)
         .align_y(iced::Center),
         Space::new().height(8),
-        text(
-            "Used for the first save of a new drawing. Existing drawings keep their file type and version."
-        )
+        text(crate::tr!("options-default-save-format-help"))
         .size(11)
         .width(sizing.width),
         Space::new().height(22),
-        text("Theme").size(15),
+        text(crate::tr!("options-theme-section")).size(15),
         Space::new().height(10),
         row![
-            text("Iced theme:").size(12).width(150),
+            text(crate::tr!("options-theme-label")).size(12).width(150),
             iced::widget::pick_list(
                 selected_theme,
                 theme_options,
@@ -102,9 +116,7 @@ pub fn view_window<'a>(
         .spacing(12)
         .align_y(iced::Center),
         Space::new().height(8),
-        text(
-            "Changing a base colour switches to Custom. Iced generates every component shade from these six colours."
-        )
+        text(crate::tr!("options-theme-help"))
         .size(11)
         .width(sizing.width),
         Space::new().height(12),