fix(ux-audit): CRITICAL + HIGH fixes — a11y, reduced-motion, forms, keyboard nav

Global (globals.css):
- prefers-reduced-motion: désactive toutes les animations/transitions
- focus-visible:ring global sur tous les éléments interactifs

Search modal:
- role="dialog" + aria-modal="true" + aria-label
- onClick backdrop ferme la modale

Insights peek:
- DOMPurify.sanitize() sur dangerouslySetInnerHTML (XSS fix)

Login form:
- autoComplete="email" / "current-password"
- htmlFor sur tous les labels

Register form:
- autoComplete="name" / "email" / "new-password"
- htmlFor sur tous les labels

GridCard (notes-list-views):
- Actions visibles sur mobile (opacity-100 sm:opacity-0)
- aria-sort sur colonne triable
- role="button" + tabIndex + onKeyDown sur lignes table

Editorial view:
- role="button" + tabIndex + onKeyDown sur articles
- Menu trigger aria-label + visible mobile

Toolbar:
- aria-label voice i18n

memento-note/components/login-form.tsx

@@ -86,7 +86,7 @@ export function LoginForm({
 
         <form action={dispatch} className="space-y-4">
           <div className="space-y-1.5">
-            <label className="text-[10px] uppercase tracking-widest font-bold text-[var(--muted-foreground)] px-4">
+            <label htmlFor="email" className="text-[10px] uppercase tracking-widest font-bold text-[var(--muted-foreground)] px-4">
               {t('auth.email')}
             </label>
             <div className="relative group">
@@ -98,6 +98,7 @@ export function LoginForm({
                 id="email"
                 type="email"
                 name="email"
+                autoComplete="email"
                 placeholder={t('auth.emailPlaceholder')}
                 required
               />
@@ -106,7 +107,7 @@ export function LoginForm({
 
           <div className="space-y-1.5">
             <div className="flex justify-between items-center px-4">
-              <label className="text-[10px] uppercase tracking-widest font-bold text-[var(--muted-foreground)]">
+              <label htmlFor="password" className="text-[10px] uppercase tracking-widest font-bold text-[var(--muted-foreground)]">
                 {t('auth.password')}
               </label>
               <Link
@@ -125,6 +126,7 @@ export function LoginForm({
                 id="password"
                 type="password"
                 name="password"
+                autoComplete="current-password"
                 placeholder="••••••••"
                 required
                 minLength={6}