Remove the RepoISO integration; keep generic support for shares of other services

RepoISO now manages the NAS itself, so nasmon no longer polls it (settings field, dashboard card,
menu link and repoiso:* alerts are gone). Drop-in SMB includes, read-only listing and keeping
smbd/nfs-server running for other software's shares stay.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/templates/settings.html

@@ -67,17 +67,6 @@
   <p class="muted small">Tests start only for disks that are awake. A long test on a large HDD takes many hours; disk stays usable.</p>
 </section>
 
-<section class="card">
-  <h2>Integrations</h2>
-  <div class="form-grid">
-    <label class="wide">RepoISO URL <input name="repoiso_url" value="{{$c.Integrations.RepoISOURL}}" placeholder="http://127.0.0.1"></label>
-  </div>
-  <p class="muted small">RepoISO (ISO library, apt/dnf repositories, Proxmox ISO exports) on this host. nasmon polls
-    <span class="mono">&lt;url&gt;/api/integration/status</span> every minute, shows a dashboard card, alerts when the portal
-    or its worker is down, and adds a menu link. Use the local address (<span class="mono">http://127.0.0.1</span>) — the
-    status endpoint only answers on loopback. Empty disables the integration.</p>
-</section>
-
 <div class="actions">
   <button type="submit" name="action" value="save">Save</button>
   <button type="submit" name="action" value="test" class="secondary">Save &amp; send test e-mail</button>