Shares of other services and RepoISO integration

- include SMB drop-ins from /etc/samba/smb.conf.d into the generated smb.conf
- keep smbd/nfs-server running while other services (/etc/exports.d, drop-ins) share,
  instead of disabling them when nasmon has no shares of its own
- list those shares read-only on /shares
- settings: RepoISO URL; poll its /api/integration/status, dashboard card, menu link,
  alerts for portal down, stale worker, failed jobs, unmounted publications

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

internal/web/templates/shares.html

@@ -140,5 +140,26 @@
   </details>
   <p class="muted small">Linux: <span class="mono">sudo mount -t nfs {{.Host}}:/nas_pool_1_8_gb/documents /mnt/nas</span>; list exports with <span class="mono">showmount -e {{.Host}}</span>.</p>
 </section>
+
+{{if .External}}
+<section class="card" id="external">
+  <h2>Shares of other services <span class="muted small">read-only</span></h2>
+  <p class="muted small">Defined by other software on this host in <span class="mono">/etc/samba/smb.conf.d/*.conf</span>
+    (included into smb.conf) and <span class="mono">/etc/exports.d/*.exports</span>. Manage them in that software;
+    nasmon keeps smbd / nfs-server running while any of them exist.</p>
+  <div class="tablewrap"><table>
+    <thead><tr><th>Type</th><th>Source</th><th>Name</th><th>Path</th><th>Clients</th></tr></thead>
+    <tbody>
+    {{range .External}}<tr>
+      <td><span class="badge">{{if eq .Kind "smb"}}SMB{{else}}NFS{{end}}</span></td>
+      <td>{{if eq .Source "repoiso"}}{{if $.RepoISO}}<a href="{{$.RepoISO}}/proxmox" target="_blank" rel="noopener">RepoISO</a>{{else}}RepoISO{{end}}{{else}}{{.Source}}{{end}}</td>
+      <td class="mono">{{if .Name}}\\{{$.Data.Host}}\{{.Name}}{{else}}—{{end}}</td>
+      <td class="mono small">{{.Path}}</td>
+      <td class="mono small">{{.Clients}}</td>
+    </tr>{{end}}
+    </tbody>
+  </table></div>
+</section>
+{{end}}
 {{end}}
 {{end}}