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/app/(main)/layout.tsx

@@ -5,6 +5,9 @@ import { ProvidersWrapper } from "@/components/providers-wrapper";
 import { auth } from "@/auth";
 import { detectUserLanguage } from "@/lib/i18n/detect-user-language";
 import { loadTranslations } from "@/lib/i18n/load-translations";
+import { getAISettings } from "@/app/actions/ai-settings";
+
+import { AIChat } from "@/components/ai-chat";
 
 export default async function MainLayout({
   children,
@@ -20,6 +23,12 @@ export default async function MainLayout({
   // Load initial translations server-side to prevent hydration mismatch
   const initialTranslations = await loadTranslations(initialLanguage);
 
+  // Load AI settings to conditionally render AI features
+  const aiSettings = session?.user?.id
+    ? await getAISettings(session.user.id)
+    : null;
+  const showAIAssistant = aiSettings?.paragraphRefactor !== false;
+
   return (
     <ProvidersWrapper initialLanguage={initialLanguage} initialTranslations={initialTranslations}>
       <div className="bg-background-light dark:bg-background-dark font-display text-slate-900 dark:text-white overflow-hidden h-screen flex flex-col">
@@ -27,7 +36,7 @@ export default async function MainLayout({
         <HeaderWrapper user={session?.user} />
 
         {/* Main Layout */}
-        <div className="flex flex-1 overflow-hidden">
+        <div className="flex flex-1 overflow-hidden relative">
           {/* Sidebar Navigation - Style Keep */}
           <Suspense fallback={<div className="w-64 flex-none hidden md:flex" />}>
             <Sidebar className="w-64 flex-none flex-col bg-white dark:bg-[#1e2128] border-e border-slate-200 dark:border-slate-800 overflow-y-auto hidden md:flex" user={session?.user} />
@@ -37,8 +46,12 @@ export default async function MainLayout({
           <main className="flex min-h-0 flex-1 flex-col overflow-y-auto bg-background-light dark:bg-background-dark p-4 scroll-smooth">
             {children}
           </main>
+
+          {/* AI Chat Drawer — only shown if user has Assistant IA enabled */}
+          {showAIAssistant && <AIChat />}
         </div>
       </div>
     </ProvidersWrapper>
   );
 }
+