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/sections/SectionPlaceholder.tsx

@@ -1,6 +1,7 @@
 import React from 'react';
 import { SIDEBAR_SECTION_CONFIG_MAP, SIDEBAR_SECTION_DESCRIPTIONS } from '@/constants/sidebar';
 import type { SidebarSection } from '@/constants/sidebar';
+import { useI18n } from '@/lib/i18n';
 
 interface SectionPlaceholderProps {
     sectionId: SidebarSection;
@@ -8,6 +9,7 @@ interface SectionPlaceholderProps {
 }
 
 export const SectionPlaceholder: React.FC<SectionPlaceholderProps> = ({ sectionId, variant }) => {
+    const { t } = useI18n();
     const config = SIDEBAR_SECTION_CONFIG_MAP[sectionId];
     const Icon = config.icon;
 
@@ -36,7 +38,7 @@ export const SectionPlaceholder: React.FC<SectionPlaceholderProps> = ({ sectionI
                     {SIDEBAR_SECTION_DESCRIPTIONS[sectionId]}
                 </p>
             </div>
-            <p className="typography-meta text-muted-foreground/60">Coming soon...</p>
+            <p className="typography-meta text-muted-foreground/60">{t('settings.common.state.comingSoon')}</p>
         </div>
     );
 };