Make the workspace right pane a first-class tab host (#3287)

* feat(app): add persistent workspace side panes

Keep the common review and file-browsing workflow beside the active agent without tearing down pane contents. Workspace tabs now share one compact chip language, assistant file links route into the retained right pane, and diff/file trees share stable geometry.

* fix(app): localize pull request empty state

* test(app): update explorer pane coverage

* fix(app): preserve explorer pane workflows

* test(app): make explorer tab selection idempotent

* fix(app): persist workspace review pins

* fix(app): preserve sidebar scrim drag hook

* fix(app): restore companion pane interactions

* test(app): follow selected sidebar surface

packages/app/src/i18n/resources/ar.ts

@@ -587,6 +587,7 @@ export const ar: TranslationResources = {
         renameAgent: "إعادة تسمية الوكيل",
       },
       actions: {
+        newTab: "علامة تبويب جديدة",
         newAgent: "وكيل جديد",
         newTerminal: "محطة جديدة",
         preparingTerminal: "إعداد علامة التبويب المحطة الطرفية",
@@ -595,6 +596,9 @@ export const ar: TranslationResources = {
         exitFocusMode: "إنهاء وضع التركيز",
         splitRight: "تقسيم الجزء الأيمن",
         splitDown: "تقسيم الجزء لأسفل",
+        changes: "التغييرات",
+        files: "الملفات",
+        pullRequest: "طلب السحب",
         terminalProfilesMenu: "Terminal profiles",
         editTerminalProfiles: "Edit profiles…",
         pinTarget: "تثبيت",
@@ -1658,6 +1662,17 @@ export const ar: TranslationResources = {
         reloadMessage: "ستفقد تغييراتك المحلية.",
       },
     },
+    files: {
+      label: "الملفات",
+      subtitle: "ملفات مساحة العمل",
+      tooltip: "تصفح ملفات مساحة العمل",
+    },
+    pullRequest: {
+      label: "طلب السحب",
+      subtitle: "تفاصيل طلب السحب",
+      emptyTitle: "لا يوجد طلب سحب بعد",
+      emptyDescription: "أنشئ طلب سحب لنسخة العمل هذه لعرض تفاصيله هنا.",
+    },
     diff: {
       changesLabel: "التغييرات",
       changesSubtitle: "فروقات شجرة العمل",