feat: section Profil (langue) + ghost text lie a la langue

- Section Profil dans Configuration: langue (fr/en/es/de), nom
- Persistance localStorage (obsigate-lang, obsigate-name)
- Ghost text adapte le prompt a la langue du profil
- CSS profile-form, config-select stylise

frontend/style.css

@@ -2215,6 +2215,19 @@ select {
   background: var(--accent);
   color: #fff;
 }
+/* Profile section */
+.profile-form { max-width: 420px; }
+.profile-field { margin-bottom: 14px; }
+.profile-field label { display: block; font-size: 0.75rem; font-weight: 600; color: var(--text-primary); margin-bottom: 4px; }
+.profile-field .config-input,
+.profile-field .config-select {
+  width: 100%; padding: 6px 10px; font-size: 0.8rem;
+  background: var(--bg-primary); color: var(--text-primary);
+  border: 1px solid var(--border); border-radius: 6px;
+  font-family: inherit;
+}
+.profile-hint { display: block; font-size: 0.65rem; color: var(--text-muted); margin-top: 4px; }
+.profile-saved { font-size: 0.7rem; color: var(--accent-green); margin-left: 10px; }
 .saved-search-vault {
   font-size: 0.65rem;
   color: var(--text-muted);