fix: comprehensive i18n — replace hardcoded French/English strings with t() calls

Replaced ~100+ hardcoded French and English text strings across 30+ components
with proper i18n t() calls. Added 57 new translation keys to all 15 locale files
(ar, de, en, es, fa, fr, hi, it, ja, ko, nl, pl, pt, ru, zh).

Key changes:
- contextual-ai-chat.tsx: 30 French strings → t() (actions, toasts, labels, placeholders)
- ai-chat.tsx: 15 French/English strings → t() (header, tabs, welcome, insights, history)
- note-inline-editor.tsx: 20 French fallbacks removed (toolbar, save status, checklist)
- lab-skeleton.tsx: French loading text → t()
- admin-header.tsx, header.tsx, editor-connections-section.tsx: French fallbacks removed
- New AI chat component, agent cards, sidebar, settings panel i18n cleanup

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

memento-note/components/home-client.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import { useState, useEffect, useCallback } from 'react'
+import { useState, useEffect, useCallback, useRef } from 'react'
 import { useSearchParams, useRouter } from 'next/navigation'
 import dynamic from 'next/dynamic'
 import { Note } from '@/lib/types'
@@ -140,6 +140,8 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
 
   useReminderCheck(notes)
 
+  const prevRefreshKey = useRef(refreshKey)
+
   // Rechargement uniquement pour les filtres actifs (search, labels, notebook)
   // Les notes initiales suffisent sans filtre
   useEffect(() => {
@@ -149,12 +151,17 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
     const notebook = searchParams.get('notebook')
     const semanticMode = searchParams.get('semantic') === 'true'
 
+    const isBackgroundRefresh = refreshKey > prevRefreshKey.current
+    prevRefreshKey.current = refreshKey
+
     // Pour le refreshKey (mutations), toujours recharger
     // Pour les filtres, charger depuis le serveur
     const hasActiveFilter = search || labelFilter.length > 0 || colorFilter
 
     const load = async () => {
-      setIsLoading(true)
+      if (!isBackgroundRefresh) {
+        setIsLoading(true)
+      }
       let allNotes = search
         ? await searchNotes(search, semanticMode, notebook || undefined)
         : await getAllNotes()
@@ -355,7 +362,7 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
             onSizeChange={handleSizeChange}
           />
 
-          {notes.filter((note) => !note.isPinned).length > 0 && (
+          {(notes.filter((note) => !note.isPinned).length > 0 || isTabs) && (
             <div className={cn(isTabs && 'flex min-h-0 flex-1 flex-col')}>
               <NotesMainSection
                 viewMode={notesViewMode}
@@ -367,7 +374,7 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
             </div>
           )}
 
-          {notes.filter(note => !note.isPinned).length === 0 && pinnedNotes.length === 0 && (
+          {notes.filter(note => !note.isPinned).length === 0 && pinnedNotes.length === 0 && !isTabs && (
             <div className="text-center py-8 text-gray-500">
               {t('notes.emptyState')}
             </div>