Add 3x-ui VLESS configs and guest access without registration.

Guests can open a public link to view or create VPN configs; panel creates VLESS clients via the 3x-ui API.

Co-authored-by: Cursor <cursoragent@cursor.com>

templates/login.html

@@ -131,6 +131,15 @@
                         <div class="spinner hidden" id="loginSpinner"></div>
                     </button>
                 </form>
+
+                {% if guest_link %}
+                <div style="margin-top: var(--space-lg); text-align: center; border-top: 1px solid var(--border-color); padding-top: var(--space-md);">
+                    <a href="{{ guest_link }}" class="btn btn-secondary" style="width:100%; text-decoration:none;">
+                        {{ _('guest_access_btn') }}
+                    </a>
+                    <div class="form-hint" style="margin-top: var(--space-xs);">{{ _('guest_access_login_hint') }}</div>
+                </div>
+                {% endif %}
             </div>
         </div>
     </div>