feat(chat): desktop prompt navigator rail (#2054)

* feat(chat): add desktop prompt navigator rail

Add a ChatGPT-style right-center prompt marker rail for web/desktop chat
with hover/keyboard preview panel, load-more for partial history (panel only),
Chat setting, and mod+alt+p shortcut. Disabled in VS Code across rail,
shortcut, settings, help, and search surfaces.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* fix(ui): read promptNavigatorEnabled from getState in shortcut handler

Match the file convention used by other shortcut handlers so the toggle
does not rely on a hook-level selector closure.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* fix(ui): drop use-no-memo and default prompt navigator off

Remove the project-unprecedented React Compiler opt-out, and ship the
prompt navigator as opt-in to match other recent chat UI toggles.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/lib/i18n/messages/ja.ts

@@ -1559,6 +1559,7 @@ export const dict: Record<I18nKey, string> = {
   'helpDialog.item.createNewSession': '新しいセッションを作成',
   'helpDialog.item.createNewWorktreeDraft': '新しいワークツリー下書きを作成',
   'helpDialog.item.focusChatInput': 'チャット入力にフォーカス',
+  'helpDialog.item.togglePromptNavigator': 'プロンプトナビゲーターの表示切替',
   'helpDialog.item.abortActiveRun': 'アクティブな実行を中止（ダブルプレス）',
   'helpDialog.item.toggleRightSidebar': '右サイドバーの切り替え',
   'helpDialog.item.openRightSidebarGitTab': '右サイドバーのGitタブを開く',
@@ -1753,6 +1754,9 @@ export const dict: Record<I18nKey, string> = {
   'chat.draftStarters.sectionSkills': 'スキル',
   'chat.draftStarters.remove': '削除',
   'chat.scrollToBottom.aria': '一番下にスクロール',
+  'chat.promptNavigator.aria': 'プロンプトナビゲーション',
+  'chat.promptNavigator.currentPrompt': '現在のプロンプト',
+  'chat.promptNavigator.loadMore': 'さらにプロンプトを読み込む',
   'chat.timeline.relative.justNow': 'たった今',
   'chat.timeline.relative.minutesAgo': '{count}分前',
   'chat.timeline.relative.hoursAgo': '{count}時間前',