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/server.go

@@ -8,7 +8,9 @@ import (
 	"io/fs"
 	"log"
 	"math"
+	"net"
 	"net/http"
+	"net/url"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -105,6 +107,7 @@ type pageData struct {
 	Data    any
 	Flash   string
 	Error   string
+	RepoISO string // browser URL of the RepoISO portal ("" = integration off)
 }
 
 // render writes a full page, or only the "content" block when ?partial=1 is
@@ -112,6 +115,7 @@ type pageData struct {
 func (s *Server) render(w http.ResponseWriter, r *http.Request, name string, pd pageData) {
 	pd.Page = name
 	pd.Partial = r.URL.Query().Get("partial") == "1"
+	pd.RepoISO = browserURL(s.cfg.Get().Integrations.RepoISOURL, r.Host)
 	if pd.Alerts == 0 {
 		pd.Alerts = len(s.sch.Status().Alerts)
 	}
@@ -288,3 +292,33 @@ func sparkline(vals []float64, max float64, class string) template.HTML {
 		`<svg class="spark %s" viewBox="0 0 %d %d" preserveAspectRatio="none"><polygon points="0,%d %s %d,%d"/><polyline points="%s"/></svg>`,
 		class, int(w), int(h), int(h), p, int(w), int(h), p))
 }
+
+// browserURL turns the configured RepoISO address into one the user's browser
+// can open: a loopback host is replaced by the host the browser used for nasmon.
+func browserURL(cfg, reqHost string) string {
+	if cfg == "" {
+		return ""
+	}
+	u, err := url.Parse(cfg)
+	if err != nil || u.Host == "" {
+		return cfg
+	}
+	switch u.Hostname() {
+	case "127.0.0.1", "localhost", "::1":
+		host := reqHost
+		if h, _, err := net.SplitHostPort(reqHost); err == nil {
+			host = h
+		}
+		if host == "" {
+			return cfg
+		}
+		if strings.Contains(host, ":") {
+			host = "[" + host + "]"
+		}
+		if p := u.Port(); p != "" {
+			host += ":" + p
+		}
+		u.Host = host
+	}
+	return u.String()
+}