fix(gui): correct wg dump indexes, status, traffic, UX improvements

- Fix off-by-one bug in wg_dump(): handshake was read from parts[5] (rx_bytes),
  now correctly reads from parts[4]; rx/tx shifted accordingly
- Run wg show via sudo to work under unprivileged wgadmin user
- Remove NoNewPrivileges from systemd service (needed for sudo)
- Merge Handshake column into Status badge (shows "online · 2м назад")
- Add humanize_ago() for human-readable handshake time
- Add next_free_ip() to suggest next available IP in new peer form
- Add device type quick-select buttons (Phone/Laptop/PC/Router/Server/Tablet)
- Placeholder in AllowedIPs now shows the real next free IP
- Traffic column shows ↓ rx / ↑ tx separately

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gui/templates/index.html

@@ -22,7 +22,6 @@
           <th>IP</th>
           <th>Роуты</th>
           <th>Endpoint</th>
-          <th>Handshake</th>
           <th>RX / TX</th>
           <th>Публичный ключ</th>
           <th>Действия</th>
@@ -33,15 +32,19 @@
         <tr class="{{ 'row-disabled' if not p.enabled else '' }}">
           <td><span class="peer-name">{{ p.name }}</span></td>
           <td>
-            <span class="badge {{ p.status }}">
-              <i class="dot"></i>{{ p.status }}
+            <span class="badge {{ p.status }}" title="{{ p.handshake_ago }}">
+              <i class="dot"></i>
+              <span>{{ p.status }}</span>
+              <span class="badge-ago">{{ p.handshake_ago }}</span>
             </span>
           </td>
           <td class="mono-sm">{{ p.client_address }}</td>
           <td class="mono-sm text-muted">{{ p.routes }}</td>
           <td class="mono-sm text-muted">{{ p.endpoint }}</td>
-          <td class="text-muted">{{ p.latest_handshake }}</td>
-          <td class="text-muted">{{ p.rx }} / {{ p.tx }}</td>
+          <td class="text-muted traffic">
+            <span title="Получено">↓ {{ p.rx }}</span>
+            <span title="Отправлено">↑ {{ p.tx }}</span>
+          </td>
           <td><span class="pubkey" title="{{ p.public_key }}">{{ p.public_key[:20] }}…</span></td>
           <td>
             <div class="actions">
@@ -77,7 +80,7 @@
         </tr>
         {% else %}
         <tr>
-          <td colspan="9" class="empty">Пиров нет. <a href="{{ url_for('new_peer') }}">Добавить первый</a></td>
+          <td colspan="8" class="empty">Пиров нет. <a href="{{ url_for('new_peer') }}">Добавить первый</a></td>
         </tr>
         {% endfor %}
       </tbody>