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/dashboard.html

@@ -104,6 +104,26 @@
   </table></div>
 </section>
 
+{{with .S.RepoISO}}
+<section class="card" id="repoiso">
+  <h2>RepoISO {{if $.RepoISO}}<a class="muted small" href="{{$.RepoISO}}" target="_blank" rel="noopener">open ↗</a>{{end}}
+    {{if not .Reachable}}<span class="badge crit">not responding</span>
+    {{else if not .WorkerAlive}}<span class="badge warn">worker stopped</span>
+    {{else}}<span class="badge ok">running</span>{{end}}
+    {{if .Version}}<span class="muted small">v{{.Version}}</span>{{end}}</h2>
+  {{if not .Reachable}}<div class="flash crit">{{.URL}}/api/integration/status: {{.Error}}</div>{{else}}
+  <div class="tablewrap"><table class="compact">
+    <tbody>
+      <tr><td class="muted">Images</td><td class="num">{{.Images}}</td><td>{{bytes .ImagesBytes}}{{if .ImagesPending}} · <span class="muted">{{.ImagesPending}} being checked</span>{{end}}{{if .ImagesError}} · <span class="crit">{{.ImagesError}} with errors</span>{{end}}</td></tr>
+      <tr><td class="muted">Publications</td><td class="num">{{.Publications}}</td><td>{{if .PublicationsError}}<span class="badge warn">{{.PublicationsError}} not mounted</span>{{else}}<span class="muted">HTTP repositories / file trees</span>{{end}}</td></tr>
+      <tr><td class="muted">Jobs</td><td class="num">{{.JobsActive}}</td><td>{{if .JobsActive}}active{{else}}<span class="muted">idle</span>{{end}}{{if .JobsFailed24h}} · <span class="badge warn">{{.JobsFailed24h}} failed in 24 h</span>{{end}}</td></tr>
+      <tr><td class="muted">Proxmox exports</td><td class="num">{{.Exports}}</td><td class="muted">NFS / SMB shares — listed on <a href="/shares#external">Shares</a></td></tr>
+      <tr><td class="muted">Worker</td><td></td><td class="small">{{if .WorkerHeartbeat}}last heartbeat {{.WorkerHeartbeat}}{{else}}no heartbeat yet{{end}}</td></tr>
+    </tbody>
+  </table></div>{{end}}
+</section>
+{{end}}
+
 <section class="card">
   <h2>Datasets</h2>
   <div class="tablewrap"><table>