feat: localize control-bar button titles and rename to Design Mode

Rename the collapse-editor toggle's expanded-state title from
"Switch to Visual Edit" to "Switch to Design Mode" so it matches
the rest of the feature's naming (command id, menu item, body
class, WorkspaceManager API all already use "design mode").

Also localize the control bar's hardcoded English titles:
- Switch to Design Mode / Switch to Code Editor get new string
  keys (CCB_SWITCH_TO_DESIGN_MODE, CCB_SWITCH_TO_CODE_EDITOR).
- Sidebar toggle, Undo, Redo, Save reuse existing
  CMD_TOGGLE_SIDEBAR / CMD_UNDO / CMD_REDO / CMD_FILE_SAVE.
- Search / Back / Forward were already localized via
  NavigationProvider.updateTooltips.

HTML keeps the English titles as fallback; the JS init overwrites
them with the localized strings so the user's locale shows on
first render.

Author: abose

src/index.html

@@ -936,7 +936,7 @@
     <!-- Vertical control bar between sidebar and editor content -->
     <div id="centralControlBar" class="no-focus">
         <div class="ccb-group ccb-group-top">
-            <a href="#" id="ccbCollapseEditorBtn" class="ccb-btn" title="Switch to Visual Edit">
+            <a href="#" id="ccbCollapseEditorBtn" class="ccb-btn" title="Switch to Design Mode">
                 <i class="fa-solid fa-feather"></i>
             </a>
             <a href="#" id="ccbSidebarToggleBtn" class="ccb-btn" title="Toggle sidebar">

src/nls/root/strings.js

@@ -930,6 +930,8 @@ define({
     "CMD_SHOW_SIDEBAR": "Show Sidebar",
     "CMD_TOGGLE_SIDEBAR": "Toggle Sidebar",
     "CMD_TOGGLE_DESIGN_MODE": "Toggle Design Mode",
+    "CCB_SWITCH_TO_DESIGN_MODE": "Switch to Design Mode",
+    "CCB_SWITCH_TO_CODE_EDITOR": "Switch to Code Editor",
     "CMD_TOGGLE_TABBAR": "File Tab Bar",
     "CMD_TOGGLE_PANELS": "Toggle Panels",
     "CMD_TOGGLE_PURE_CODE": "No Distractions",

src/view/CentralControlBar.js

@@ -237,7 +237,7 @@ define(function (require, exports, module) {
         $("body").toggleClass("ccb-editor-collapsed", editorCollapsed);
         const $collapseBtn = $("#ccbCollapseEditorBtn");
         $collapseBtn.toggleClass("is-active", editorCollapsed)
-            .attr("title", editorCollapsed ? "Switch to Code Editor" : "Switch to Visual Edit");
+            .attr("title", editorCollapsed ? Strings.CCB_SWITCH_TO_CODE_EDITOR : Strings.CCB_SWITCH_TO_DESIGN_MODE);
         $collapseBtn.find("i").attr("class", editorCollapsed ? "fa-solid fa-code" : "fa-solid fa-feather");
         if (_toggleDesignModeCommand) {
             _toggleDesignModeCommand.setChecked(editorCollapsed);
@@ -304,6 +304,15 @@ define(function (require, exports, module) {
         $fileName = $fileLabel.find(".ccb-file-name");
 
         _wireButtons();
+        // The HTML titles on the control-bar buttons are fallback English
+        // strings; set the localized versions up front so the initial render
+        // reflects the user's locale. (searchNav / navBackButton /
+        // navForwardButton get their localized titles from NavigationProvider.)
+        $("#ccbCollapseEditorBtn").attr("title", Strings.CCB_SWITCH_TO_DESIGN_MODE);
+        $("#ccbSidebarToggleBtn").attr("title", Strings.CMD_TOGGLE_SIDEBAR);
+        $("#ccbUndoBtn").attr("title", Strings.CMD_UNDO);
+        $("#ccbRedoBtn").attr("title", Strings.CMD_REDO);
+        $("#ccbSaveBtn").attr("title", Strings.CMD_FILE_SAVE);
         _syncLeftPositions();
 
         // While the sidebar is being dragged we only reposition CCB / main-toolbar.