feat(ui): redesign the default shortcut layout around a mod+k leader

Single chords stay for everyday actions; open/go actions move to two-step
mod+k sequences; held mod+digit switches header session tabs and held
mod+alt+digit switches context panel surfaces. Rare actions leave the
shortcut schema for the command palette, every remaining action ships with
a default binding, and stored overrides from the old layout reset once.
Key matching now follows the physical key on non-Latin layouts and for
Option-modified digits on macOS, including in the recording dialog.

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

@@ -1143,9 +1143,8 @@ export const settingsDict = {
   'settings.openchamber.keyboardShortcuts.action.toggle_terminal_expanded.label': 'ターミナル拡大の切替',
   'settings.openchamber.keyboardShortcuts.action.add_selection_to_chat.label': '選択範囲をチャットに追加',
   'settings.openchamber.keyboardShortcuts.action.toggle_sidebar.label': 'サイドバーの切替',
-  'settings.openchamber.keyboardShortcuts.action.toggle_right_sidebar.label': 'コンテキストパネルの表示切替',
-  'settings.openchamber.keyboardShortcuts.action.open_right_sidebar_git.label': 'Git サーフェスを開く',
-  'settings.openchamber.keyboardShortcuts.action.open_right_sidebar_files.label': 'ファイルサーフェスを開く',
+    'settings.openchamber.keyboardShortcuts.action.switch_session_tab.label': 'セッションタブを切り替え',
+  'settings.openchamber.keyboardShortcuts.action.switch_session_tab.suffix': ' + 1…9',
   'settings.openchamber.keyboardShortcuts.action.switch_context_surface.label': 'コンテキストパネルのサーフェスを切り替え',
   'settings.openchamber.keyboardShortcuts.action.switch_context_surface.suffix': ' + 1…0',
   'settings.openchamber.keyboardShortcuts.action.new_chat.label': '新しい Session',
@@ -1153,9 +1152,7 @@ export const settingsDict = {
   'settings.openchamber.keyboardShortcuts.action.new_chat_worktree.label': '新しい Worktree 下書き',
   'settings.openchamber.keyboardShortcuts.action.new_mini_chat.label': '新しいミニチャットウィンドウ',
   'settings.openchamber.keyboardShortcuts.action.open_help.label': 'キーボードショートカットを開く',
-  'settings.openchamber.keyboardShortcuts.action.toggle_context_plan.label': '計画コンテキストパネルの切替',
   'settings.openchamber.keyboardShortcuts.action.toggle_services_menu.label': 'サービスメニューの切替',
-  'settings.openchamber.keyboardShortcuts.action.cycle_services_tab.label': 'サービスタブを順に切替',
   'settings.openchamber.keyboardShortcuts.action.cycle_theme.label': 'テーマを順に切替',
   'settings.openchamber.keyboardShortcuts.action.cycle_agent.label': 'Agent を順に切替',
   'settings.openchamber.keyboardShortcuts.action.cycle_favorite_model_forward.label': 'お気に入りモデルを次へ',