[FIX] register.html: ?invite= auto-fill + placeholder corretto; lookup-piva: 500->404 graceful

public/register.html

@@ -209,7 +209,7 @@
                         <div class="form-group">
                             <label class="form-label" for="invite-code">Codice Invito</label>
                             <input type="text" id="invite-code" class="form-input"
-                                   placeholder="es. NIS2-XXXX-YYYY" autocomplete="off"
+                                   placeholder="es. inv_a1b2c3d4e5f6..." autocomplete="off"
                                    oninput="validateInvite(this.value)">
                             <div class="lookup-status" id="invite-status"></div>
                         </div>
@@ -344,8 +344,9 @@
                 if (document.getElementById('card-' + r)) selectRole(r);
             });
         }
-        if (params.get('invite_token')) {
-            inviteToken = params.get('invite_token');
+        const _inviteTok = params.get('invite_token') || params.get('invite') || params.get('token');
+        if (_inviteTok) {
+            inviteToken = _inviteTok;
             document.addEventListener('DOMContentLoaded', () => {
                 const details = document.getElementById('invite-details');
                 details.open = true;
@@ -372,7 +373,7 @@
         (function() {
             const r = params.get('role');
             if (r && document.getElementById('card-' + r)) selectRole(r);
-            const tok = params.get('invite_token');
+            const tok = params.get('invite_token') || params.get('invite') || params.get('token');
             if (tok) {
                 inviteToken = tok;
                 document.getElementById('invite-details').open = true;