docs+chore: refresh README/STATE, cache electron in CI, lock chord by keycode, misc P3

- README: add lock-screen section, refresh test list (13 offline tests),
  updater fallback order, data locations, architecture tree
- STATE.md: v1.0.20, current release.cjs flow (no --skip-github), M11-M13
- ci.yml: actions/cache for the ~100MB Electron binary keyed on lockfile
- .gitignore: ignore .env.* but keep committed templates
- scripts/archive-releases.cjs moved in from tmp-test; KEEP_TAG is now a
  required CLI arg (a hardcoded default is how the wrong version gets wiped)
- lockShortcuts: isPanicLockChord matches input.code ('KeyL') so Dvorak and
  non-Latin layouts trigger Ctrl+L lock correctly
- settings: drop the dead single-option update-channel Select from About tab
- Workspace/App: memo(IconRail/LayoutFlyout), useMemo layoutMenu keyed on
  language, useCallback onOpenSettings; drop unused IconRail onSplit prop

src/main/lockShortcuts.ts

@@ -6,6 +6,8 @@
 
 export interface LockInputEvent {
   key: string
+  /** Physical key position (`KeyL`, `F5`, …) — layout-independent, unlike `key`. */
+  code: string
   control: boolean
   shift: boolean
   alt: boolean
@@ -45,6 +47,12 @@ export function isLockBlockedShortcut(input: LockInputEvent): boolean {
  * because Ctrl+Shift+L is the switch-to-English chord on Chinese and Japanese
  * IMEs; Alt is excluded because AltGr arrives as Ctrl+Alt on most European
  * layouts. A chord that isn't exactly this must keep its original meaning.
+ *
+ * Matching is on `input.code` (the physical key) rather than `input.key`: the
+ * key character depends on the active keyboard layout, so on Dvorak or a
+ * non-Latin layout the physical L key no longer arrives as 'l' and matching
+ * `key === 'l'` would silently stop locking. The code names the key position
+ * and is identical on every layout.
  */
 export function isPanicLockChord(input: LockInputEvent): boolean {
   return (
@@ -52,6 +60,6 @@ export function isPanicLockChord(input: LockInputEvent): boolean {
     !input.shift &&
     !input.alt &&
     !input.meta &&
-    input.key.toLowerCase() === 'l'
+    input.code === 'KeyL'
   )
 }

src/renderer/src/App.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react'
+import { useCallback, useEffect, useState } from 'react'
 import { ConfigProvider } from 'antd'
 import zhCN from 'antd/locale/zh_CN'
 import zhTW from 'antd/locale/zh_TW'
@@ -46,6 +46,9 @@ export default function App(): React.JSX.Element {
   const tabAccentColor = useSettingsStore((s) => s.settings.terminal.tabAccentColor)
   const storedLanguage = useSettingsStore((s) => s.settings.system.language ?? DEFAULT_LANGUAGE)
   const [settingsOpen, setSettingsOpen] = useState(false)
+  // Stable so the memoized icon rail inside Workspace can bail out of the
+  // re-renders Workspace does on every session/panel change.
+  const openSettings = useCallback((): void => setSettingsOpen(true), [])
   /** Secure default: main may already hold a startup lock before this IPC
    *  resolves, so the shell must not become interactive while unknown. `null`
    *  means "not answered yet" and is kept distinct from "locked": the overlay
@@ -171,7 +174,7 @@ export default function App(): React.JSX.Element {
             before the browser checks for a focused descendant. */}
         <div className="app-root" inert={locked || undefined} aria-hidden={locked || undefined}>
           <TitleBar />
-          <Workspace onOpenSettings={() => setSettingsOpen(true)} />
+          <Workspace onOpenSettings={openSettings} />
           <SettingsDialog open={settingsOpen} onClose={() => setSettingsOpen(false)} />
           <TransferPanel />
         </div>

src/renderer/src/settings/AboutTab.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useState } from 'react'
-import { Button, Progress, Select, Switch, Tag } from 'antd'
+import { Button, Progress, Switch, Tag } from 'antd'
 import { DEFAULT_LANGUAGE, t, type Language } from '@shared/i18n'
 import type { AppInfo, ReleaseNote, UpdateState, UpdateStatus } from '@shared/ipc'
 import { useSettingsStore } from './store'
@@ -103,11 +103,6 @@ export function AboutTab(): React.JSX.Element {
       </div>
 
       <div className="about-controls">
-        <Select
-          value="stable"
-          options={[{ value: 'stable', label: t('settings.about.channelStable') }]}
-          style={{ width: 150 }}
-        />
         <label className="about-autocheck">
           <Switch
             size="small"

src/renderer/src/workspace/Workspace.tsx

@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useRef, useState } from 'react'
+import { memo, useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import type { ReactNode } from 'react'
 import { App, Button, Checkbox, Popover, Tooltip } from 'antd'
 import type { MenuProps } from 'antd'
@@ -1152,28 +1152,34 @@ export default function Workspace({ onOpenSettings }: WorkspaceProps): React.JSX
     [message]
   )
 
-  const layoutMenu: MenuProps = {
-    items: [
-      { key: 'split-right', label: t('workspace.layout.splitRight') },
-      { key: 'split-below', label: t('workspace.layout.splitBelow') },
-      { type: 'divider' },
-      { key: 'save', label: t('workspace.layout.saveTemplate') },
-      { key: 'apply', label: t('workspace.layout.applyTemplate') }
-    ],
-    onClick: ({ key }) => {
-      if (key === 'split-right') handleSplit('right')
-      else if (key === 'split-below') handleSplit('below')
-      else if (key === 'save') setSaveOpen(true)
-      else if (key === 'apply') setApplyOpen(true)
-    }
-  }
+  // Memoized so the memoized IconRail below can actually bail out: the labels
+  // are translated at build time, so `language` has to be a dependency or a
+  // language switch would leave stale menu text behind.
+  const language = useSettingsStore((s) => s.settings.system.language)
+  const layoutMenu = useMemo<MenuProps>(
+    () => ({
+      items: [
+        { key: 'split-right', label: t('workspace.layout.splitRight') },
+        { key: 'split-below', label: t('workspace.layout.splitBelow') },
+        { type: 'divider' },
+        { key: 'save', label: t('workspace.layout.saveTemplate') },
+        { key: 'apply', label: t('workspace.layout.applyTemplate') }
+      ],
+      onClick: ({ key }) => {
+        if (key === 'split-right') handleSplit('right')
+        else if (key === 'split-below') handleSplit('below')
+        else if (key === 'save') setSaveOpen(true)
+        else if (key === 'apply') setApplyOpen(true)
+      }
+    }),
+    [language, handleSplit]
+  )
 
   return (
     <div className="workspace-root">
       <IconRail
         onOpenSettings={onOpenSettings}
         onNewTerminal={handleRailNewTerminal}
-        onSplit={handleSplit}
         onToggleSidebar={toggleSidebar}
         sidebarOpen={sidebarOpen}
         connecting={connecting}
@@ -1394,11 +1400,14 @@ function WorkspaceBroadcastPopover({
 /**
  * XTerminal-style slim icon rail on the left edge — replaces the top toolbar.
  * Top: workspace actions; bottom: settings.
+ *
+ * Memoized: the workspace re-renders on every session/panel change, and the
+ * rail only depends on sidebar visibility, the connecting spinner and the
+ * (memoized) layout menu, so the shallow compare lets it skip those renders.
  */
-function IconRail({
+const IconRail = memo(function IconRail({
   onOpenSettings,
   onNewTerminal,
-  onSplit,
   onToggleSidebar,
   sidebarOpen,
   connecting,
@@ -1406,7 +1415,6 @@ function IconRail({
 }: {
   onOpenSettings: () => void
   onNewTerminal: () => void
-  onSplit: (direction: 'right' | 'below') => void
   onToggleSidebar: () => void
   sidebarOpen: boolean
   connecting: boolean
@@ -1433,7 +1441,7 @@ function IconRail({
       <RailButton title={t('workspace.rail.settings')} icon={<SettingOutlined />} onClick={onOpenSettings} />
     </div>
   )
-}
+})
 
 /** M6.1: terminal / SSH workspace entries in the icon rail. */
 function ModeRailButtons(): React.JSX.Element {
@@ -1464,7 +1472,7 @@ function ModeRailButtons(): React.JSX.Element {
  * rail's own stacking context, opens to the right of the rail, and closes only
  * on item pick, outside pointerdown, or Escape.
  */
-function LayoutFlyout({ menu }: { menu: MenuProps }): React.JSX.Element {
+const LayoutFlyout = memo(function LayoutFlyout({ menu }: { menu: MenuProps }): React.JSX.Element {
   const [open, setOpen] = useState(false)
   const rootRef = useRef<HTMLDivElement>(null)
 
@@ -1527,7 +1535,7 @@ function LayoutFlyout({ menu }: { menu: MenuProps }): React.JSX.Element {
       )}
     </div>
   )
-}
+})
 
 function RailButton({
   title,

src/shared/i18n/dicts/en/settings.ts

@@ -307,7 +307,6 @@ const settings: Record<string, string> = {
   'settings.about.statusDownloaded': 'Download complete — restart to install',
   'settings.about.statusError': 'Check failed',
   'settings.about.statusDev': 'Update checks are unavailable in development mode',
-  'settings.about.channelStable': 'Stable channel',
   'settings.about.autoCheck': 'Check automatically at startup',
   'settings.about.download': 'Download update',
   'settings.about.downloadGithub': ' (GitHub source)',

src/shared/i18n/dicts/ja/settings.ts

@@ -302,7 +302,6 @@ const settings: Record<string, string> = {
   'settings.about.statusDownloaded': 'ダウンロード完了。再起動してインストールできます',
   'settings.about.statusError': '確認に失敗しました',
   'settings.about.statusDev': '開発モードでは更新を確認できません',
-  'settings.about.channelStable': '安定版チャンネル',
   'settings.about.autoCheck': '起動時に自動で確認',
   'settings.about.download': '更新をダウンロード',
   'settings.about.downloadGithub': '（GitHub ソース）',

src/shared/i18n/dicts/zh-CN/settings.ts

@@ -291,7 +291,6 @@ const settings: Record<string, string> = {
   'settings.about.statusDownloaded': '下载完成，可重启安装',
   'settings.about.statusError': '检查失败',
   'settings.about.statusDev': '开发模式不支持更新检查',
-  'settings.about.channelStable': '稳定更新通道',
   'settings.about.autoCheck': '启动时自动检查',
   'settings.about.download': '下载更新',
   'settings.about.downloadGithub': '（GitHub 源）',

src/shared/i18n/dicts/zh-TW/settings.ts

@@ -291,7 +291,6 @@ const settings: Record<string, string> = {
   'settings.about.statusDownloaded': '下載完成，可重新啟動安裝',
   'settings.about.statusError': '檢查失敗',
   'settings.about.statusDev': '開發模式不支援檢查更新',
-  'settings.about.channelStable': '穩定更新通道',
   'settings.about.autoCheck': '啟動時自動檢查',
   'settings.about.download': '下載更新',
   'settings.about.downloadGithub': '（GitHub 來源）',