i18n: add quick-picker strings and reduce-motion settings toggle

Five new keys across the EN source plus 24 locale variants (DE plus
23 AI-assisted, each carrying the pending-review marker): the header
quick-picker tooltip and two section headers, plus name and
description for a new ReduceMotion checkbox.

ReduceMotion was a config field with no UI -- the checkbox lands in
the Theme & Layout tab's window-style section. Designer.cs hand-edited
as a v1.5.4 block matching the v1.4.8 convention.

HellionChat/Ui/SettingsTabs/ThemeAndLayout.cs

@@ -295,6 +295,20 @@ internal sealed class ThemeAndLayout : ISettingsTab
                 Mutable.WindowOpacity = opacityPercent / 100f;
             }
             ImGuiUtil.HelpMarker(HellionStrings.Settings_ThemeAndLayout_WindowOpacity_Description);
+
+            ImGui.Spacing();
+            ImGui.Separator();
+            ImGui.Spacing();
+
+            // Master accessibility toggle for the v1.5.4 motion work: the
+            // theme crossfade, the sidebar/card hover lerps and the
+            // unread-tab pulse all read Config.ReduceMotion and snap
+            // instantly when it is on.
+            ImGui.Checkbox(
+                HellionStrings.Settings_ThemeAndLayout_ReduceMotion_Name,
+                ref Mutable.ReduceMotion
+            );
+            ImGuiUtil.HelpMarker(HellionStrings.Settings_ThemeAndLayout_ReduceMotion_Description);
         }
     }