feat: optional 4-digit PIN asked in every new tab (not on reload), on-screen keypad for phones; set, change or remove it in the account; five misses sign out

internal/server/passkeys.go

@@ -353,7 +353,7 @@ func (s *Server) handleAccount(w http.ResponseWriter, r *http.Request) {
 	for _, k := range keys {
 		list = append(list, map[string]any{"id": k.ID, "name": k.Name, "created": k.CreatedAt, "last_used": k.LastUsed})
 	}
-	writeJSON(w, map[string]any{"username": a.Username, "keys": list, "password_off": s.db.PasswordOff(a.ID)})
+	writeJSON(w, map[string]any{"username": a.Username, "keys": list, "password_off": s.db.PasswordOff(a.ID), "pin": s.db.AdminPin(a.ID) != ""})
 }
 
 // POST /api/panel/account/password/change - a new password, given the