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/alert/rules.go

@@ -40,6 +40,8 @@ type Input struct {
 	HasCPU  bool
 	RootFS  collect.FSUsage
 	RootOK  bool
+	// RepoISO is the polled RepoISO health (nil when the integration is off).
+	RepoISO *collect.RepoISO
 	// Frozen lists key prefixes whose open alerts must be left untouched
 	// because no fresh data was available for them in this cycle.
 	Frozen []string
@@ -194,10 +196,36 @@ func Evaluate(in Input) []Event {
 		}
 	}
 
+	if r := in.RepoISO; r != nil {
+		switch {
+		case !r.Reachable:
+			add("repoiso:api:down", LevelCrit, "RepoISO is not responding",
+				fmt.Sprintf("%s/api/integration/status: %s. Check: systemctl status repoiso-api nginx", r.URL, r.Error))
+		case !r.WorkerAlive:
+			add("repoiso:worker:stale", LevelWarn, "RepoISO worker is not running",
+				fmt.Sprintf("Last worker heartbeat: %s. Downloads, mounts and Proxmox exports are not processed. Check: systemctl status repoiso-worker", orNever(r.WorkerHeartbeat)))
+		}
+		if r.Reachable && r.JobsFailed24h > 0 {
+			add("repoiso:jobs:failed", LevelWarn, fmt.Sprintf("RepoISO: %d failed job(s) in 24 h", r.JobsFailed24h),
+				"See the Jobs page of RepoISO for the errors.")
+		}
+		if r.Reachable && r.PublicationsError > 0 {
+			add("repoiso:publications:error", LevelWarn, fmt.Sprintf("RepoISO: %d publication(s) not mounted", r.PublicationsError),
+				"See the Publications page of RepoISO; remount or unpublish the image.")
+		}
+	}
+
 	sort.Slice(ev, func(i, j int) bool { return ev[i].Key < ev[j].Key })
 	return ev
 }
 
+func orNever(s string) string {
+	if s == "" {
+		return "never"
+	}
+	return s
+}
+
 func humanBytes(b uint64) string {
 	const unit = 1024
 	if b < unit {