fix: i18n system overhaul and sidebar UI bugs

- Fix LanguageProvider: add RTL support (ar/fa), translation caching,
  prevent blank flash during load, browser language detection
- Fix detect-user-language: extend whitelist from 5 to all 15 languages
- Remove hardcoded initialLanguage="fr" from auth layout
- Complete fr.json translation (all sections translated from English)
- Add missing admin.ai keys to all 13 non-English locales
- Translate ai.autoLabels, ai.batchOrganization, memoryEcho sections
  for all locales
- Remove duplicate top-level autoLabels/batchOrganization from en.json
- Fix notebook creation: replace window.location.reload() with
  createNotebookOptimistic + router.refresh()
- Fix notebook name truncation in sidebar with min-w-0
- Remove redundant router.refresh() after note creation in page.tsx

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

keep-notes/lib/i18n/LanguageProvider.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import { createContext, useContext, useEffect, useState } from 'react'
+import { createContext, useContext, useEffect, useState, useCallback, useRef } from 'react'
 import type { ReactNode } from 'react'
 import { SupportedLanguage, loadTranslations, getTranslationValue, Translations } from './load-translations'
 
@@ -13,18 +13,35 @@ type LanguageContextType = {
 
 const LanguageContext = createContext<LanguageContextType | undefined>(undefined)
 
+const RTL_LANGUAGES: SupportedLanguage[] = ['ar', 'fa']
+
+function updateDocumentDirection(lang: SupportedLanguage) {
+  document.documentElement.lang = lang
+  document.documentElement.dir = RTL_LANGUAGES.includes(lang) ? 'rtl' : 'ltr'
+}
+
 export function LanguageProvider({ children, initialLanguage = 'en' }: {
   children: ReactNode
   initialLanguage?: SupportedLanguage
 }) {
   const [language, setLanguageState] = useState<SupportedLanguage>(initialLanguage)
   const [translations, setTranslations] = useState<Translations | null>(null)
+  const cacheRef = useRef<Map<SupportedLanguage, Translations>>(new Map())
 
-  // Load translations when language changes
+  // Load translations when language changes (with caching)
   useEffect(() => {
+    const cached = cacheRef.current.get(language)
+    if (cached) {
+      setTranslations(cached)
+      updateDocumentDirection(language)
+      return
+    }
+
     const loadLang = async () => {
       const loaded = await loadTranslations(language)
+      cacheRef.current.set(language, loaded)
       setTranslations(loaded)
+      updateDocumentDirection(language)
     }
     loadLang()
   }, [language])
@@ -34,7 +51,6 @@ export function LanguageProvider({ children, initialLanguage = 'en' }: {
     const saved = localStorage.getItem('user-language') as SupportedLanguage
     if (saved) {
       setLanguageState(saved)
-      document.documentElement.lang = saved
     } else {
       // Auto-detect from browser language
       const browserLang = navigator.language.split('-')[0] as SupportedLanguage
@@ -43,35 +59,44 @@ export function LanguageProvider({ children, initialLanguage = 'en' }: {
       if (supportedLangs.includes(browserLang)) {
         setLanguageState(browserLang)
         localStorage.setItem('user-language', browserLang)
-        document.documentElement.lang = browserLang
       }
     }
   }, [])
 
-  const setLanguage = (lang: SupportedLanguage) => {
+  const setLanguage = useCallback((lang: SupportedLanguage) => {
     setLanguageState(lang)
     localStorage.setItem('user-language', lang)
-    // Update HTML lang attribute for font styling
-    document.documentElement.lang = lang
-  }
+    updateDocumentDirection(lang)
+  }, [])
 
-  const t = (key: string, params?: Record<string, string | number>) => {
+  const t = useCallback((key: string, params?: Record<string, string | number>) => {
     if (!translations) return key
 
     let value: any = getTranslationValue(translations, key)
 
     // Replace parameters like {count}, {percentage}, etc.
-    if (params) {
+    if (params && typeof value === 'string') {
       Object.entries(params).forEach(([param, paramValue]) => {
         value = value.replace(`{${param}}`, String(paramValue))
       })
     }
 
-    return value
-  }
+    return typeof value === 'string' ? value : key
+  }, [translations])
 
+  // During initial load, show children with the initial language as fallback
+  // to prevent blank flash
   if (!translations) {
-    return null // Show loading state if needed
+    return (
+      <LanguageContext.Provider value={{
+        language: initialLanguage,
+        setLanguage,
+        t: (key: string) => key,
+        translations: {} as Translations
+      }}>
+        {children}
+      </LanguageContext.Provider>
+    )
   }
 
   return (

keep-notes/lib/i18n/detect-user-language.ts

@@ -49,7 +49,7 @@ export async function detectUserLanguage(): Promise<SupportedLanguage> {
     if (sortedLanguages.length > 0) {
       const topLanguage = sortedLanguages[0][0] as SupportedLanguage
       // Verify it's a supported language
-      if (['fr', 'en', 'es', 'de', 'fa'].includes(topLanguage)) {
+      if (['en', 'fr', 'es', 'de', 'fa', 'it', 'pt', 'ru', 'zh', 'ja', 'ko', 'ar', 'hi', 'nl', 'pl'].includes(topLanguage)) {
         return topLanguage
       }
     }