Add i18n foundation and translations (#1027)

* feat: add i18n foundation

* feat: localize sessions sidebar

* Localize multirun/scheduled tasks and fix dialog dropdown interactions

* localize git sidebar surface and add zh-CN keys

* feat(ui): localize context panel, diff/plan views, and context sidebar content

* fix(config): resolve user config home via fs/home before embedded home

* localize header/chat UI and complete model/worktree panel strings

* localize worktree + github issue/pr dialog flows

* localize settings sections and split settings i18n dictionaries

* localize additional settings sections and sidebars

* localize more settings pages and dialogs

* fix settings select trigger localization

* localize tunnel settings ui surface

* localize additional settings sections

* localize keyboard shortcuts labels in settings

* localize terminal and utility dialogs surfaces

* feat(i18n): localize remaining UI strings

* Add Ukrainian locale

* Add Spanish locale

* Add Brazilian Portuguese locale

* Polish locale translations

packages/ui/src/components/layout/Sidebar.tsx

@@ -1,6 +1,7 @@
 import React from 'react';
 import { cn } from '@/lib/utils';
 import { ErrorBoundary } from '../ui/ErrorBoundary';
+import { useI18n } from '@/lib/i18n';
 import { useUIStore } from '@/stores/useUIStore';
 
 export const SIDEBAR_CONTENT_WIDTH = 280;
@@ -15,6 +16,7 @@ interface SidebarProps {
 }
 
 export const Sidebar: React.FC<SidebarProps> = ({ isOpen, isMobile, children, className }) => {
+    const { t } = useI18n();
     const sidebarWidth = useUIStore((state) => state.sidebarWidth);
     const setSidebarWidth = useUIStore((state) => state.setSidebarWidth);
     const [isResizing, setIsResizing] = React.useState(false);
@@ -143,7 +145,7 @@ export const Sidebar: React.FC<SidebarProps> = ({ isOpen, isMobile, children, cl
                     onPointerCancel={handlePointerEnd}
                     role="separator"
                     aria-orientation="vertical"
-                    aria-label="Resize left panel"
+                    aria-label={t('sidebar.resize.leftPanelAria')}
                 />
             )}
             <div