Graphic Attributes: tidy helpers, split tests, translate the palette

- The hatch pattern picker takes its messages as one PatternPickerMessages
  struct instead of eight arguments.
- The palette's fill index is keyed on the scene's geometry epoch alone;
  epochs are unique across scenes, so the scene address is not needed.
- The ribbon lineweight handler is an on_ribbon_lineweight_changed method,
  used by the palette instead of a recursive update() call.
- The 430-line palette test is split into eight focused tests with shared
  helpers; no checks were dropped.
- Palette, gradient editor, prompts, messages and undo labels go through
  t!/tf!. The 33 new strings are in a graphic-attributes Fluent group in
  all 21 locales; "[Yes / No] <Yes>", ByLayer and ByBlock stay English.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VgkJN8DEojuPTumAXLHotu

src/app/update/command.rs

@@ -2155,6 +2155,32 @@ pub(super) fn on_tab_close(&mut self, idx: usize) -> Task<Message> {
                 Task::none()
     }
 
+    pub(super) fn on_ribbon_lineweight_changed(&mut self, lw: acadrust::types::LineWeight) -> Task<Message> {
+        let i = self.active_tab;
+        self.ribbon.close_dropdown();
+        let handles = self.property_target_handles(i);
+        if handles.is_empty() {
+            if self.has_property_selection(i) {
+                return Task::none();
+            }
+            // Persist into the tab's header (CELWEIGHT). #21.
+            self.tabs[i].scene.document.header.current_line_weight = lw.value();
+            self.tabs[i].dirty = true;
+            self.ribbon.active_lineweight = lw;
+        } else {
+            // Lineweight is baked into the cached wire geometry —
+            // re-tessellate so the change shows immediately (issue #231
+            // class).
+            self.apply_property_op(i, "CHPROP", &handles, |app, handle| {
+                if let Some(entity) = app.tabs[i].scene.document.get_entity_mut(handle) {
+                    crate::scene::view::dispatch::apply_line_weight(entity, lw);
+                }
+            });
+            self.ribbon.active_lineweight = lw;
+        }
+        Task::none()
+    }
+
     pub(super) fn on_ribbon_linetype_changed(&mut self, lt: String) -> Task<Message> {
                 let i = self.active_tab;
                 self.ribbon.close_dropdown();