feat(desktop): sync knowledge, recordings and shared settings; play any recording

Knowledge documents travel as source-text chunks; each surface embeds them
with its own model, the server index is requested through embed-chunks, and
documents from the phone are stored without a file and indexed from their
chunks. Chunk text is now kept when local embedding fails, so reindexing no
longer needs the original file.

Recordings upload to the mobile storage contract (audio bucket under the
user's folder plus an audio_files row, 50 MiB cap, a Settings > Cloud
toggle) and are removed with their record. The history card gains a play
button that uses the local file or, for phone recordings, a signed URL.

Language (ko/en), system/light/dark theme, auto-polish and the active user
command follow the phone's user_settings with its revision rule; changes that
arrive from the phone reach the open window.

apps/desktop/src/renderer/App.tsx

@@ -9,7 +9,7 @@
 import { useState, useEffect, useMemo, useRef } from 'react'
 import { ThemeProvider, CssBaseline, useMediaQuery } from '@mui/material'
 import { getTheme } from '@d3ro/ui/theme'
-import { I18nProvider, type I18nStorage, type Locale } from '@d3ro/i18n'
+import { I18nProvider, useI18n, type I18nStorage, type Locale } from '@d3ro/i18n'
 import { AppLayout } from './components/AppLayout'
 import { UpgradePromptModal } from './components/UpgradePromptModal'
 import { startSystemAudioCapture, stopSystemAudioCapture } from './utils/systemAudioCapture'
@@ -26,6 +26,21 @@ const electronI18nStorage: I18nStorage = {
   }
 }
 
+/** 다른 기기(모바일)에서 바꾼 언어가 동기화로 들어오면 화면 언어도 바꾼다. */
+function SyncedLocale(): null {
+  const { locale, setLocale } = useI18n()
+  useEffect(
+    () =>
+      window.electronAPI.config.onChanged((e: ConfigChangedEvent) => {
+        if (e.key === 'language' && typeof e.value === 'string' && e.value !== locale) {
+          setLocale(e.value as Locale)
+        }
+      }),
+    [locale, setLocale],
+  )
+  return null
+}
+
 export function App(): React.ReactElement {
   const [themeMode, setThemeMode] = useState<ThemeMode>('auto')
   const prefersDark = useMediaQuery('(prefers-color-scheme: dark)')
@@ -76,6 +91,7 @@ export function App(): React.ReactElement {
 
   return (
     <I18nProvider storage={electronI18nStorage}>
+      <SyncedLocale />
       <ThemeProvider theme={theme}>
         <CssBaseline />
         <AppLayout />