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/agents/agent-form.tsx

@@ -207,8 +207,11 @@ export function AgentForm({ agent, notebooks, onSave, onCancel }: AgentFormProps
   ]
 
   return (
-    <div className="fixed inset-0 bg-black/30 flex items-center justify-center z-50 p-4">
-      <div className="bg-card rounded-2xl shadow-xl max-w-lg w-full max-h-[90vh] overflow-y-auto">
+    <div className="fixed inset-0 bg-black/20 flex justify-end z-50" onClick={onCancel}>
+      <div 
+        className="bg-card shadow-2xl w-full max-w-md h-full overflow-y-auto animate-in slide-in-from-right duration-300 flex flex-col border-l border-border/40"
+        onClick={e => e.stopPropagation()}
+      >
         {/* Header — editable agent name */}
         <div className="flex items-center justify-between px-6 py-4 border-b border-border">
           <input
@@ -550,7 +553,7 @@ export function AgentForm({ agent, notebooks, onSave, onCancel }: AgentFormProps
           )}
 
           {/* Actions */}
-          <div className="flex items-center justify-end gap-3 pt-2">
+          <div className="flex items-center justify-end gap-3 pt-6 pb-4 mt-auto border-t border-border/40 bg-card sticky bottom-0">
             <button
               type="button"
               onClick={onCancel}
@@ -561,7 +564,7 @@ export function AgentForm({ agent, notebooks, onSave, onCancel }: AgentFormProps
             <button
               type="submit"
               disabled={isSaving}
-              className="px-4 py-2 text-sm font-medium text-primary-foreground bg-primary rounded-lg hover:bg-primary/90 transition-colors disabled:opacity-50"
+              className="px-4 py-2 text-sm font-medium text-primary-foreground bg-primary rounded-lg hover:bg-primary/90 transition-colors disabled:opacity-50 shadow-sm"
             >
               {isSaving ? t('agents.form.saving') : agent ? t('agents.form.save') : t('agents.form.create')}
             </button>