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/external_test.go

@@ -0,0 +1,32 @@
+package web
+
+import (
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"nasmon/internal/shares"
+)
+
+func TestSharesPageListsExternal(t *testing.T) {
+	srv, _, _ := newTestServer(t)
+	f := &shareRunner{}
+	withShareRunner(srv, f)
+	dir := t.TempDir()
+	smbDir, nfsDir := filepath.Join(dir, "smb.conf.d"), filepath.Join(dir, "exports.d")
+	_ = os.MkdirAll(smbDir, 0o755)
+	_ = os.MkdirAll(nfsDir, 0o755)
+	_ = os.WriteFile(filepath.Join(smbDir, "repoiso.conf"), []byte("[iso-pve]\n   path = /tank/iso/export/pve\n"), 0o644)
+	_ = os.WriteFile(filepath.Join(nfsDir, "repoiso.exports"), []byte("\"/tank/iso/export/pve\" 10.10.0.0/24(ro)\n"), 0o644)
+	srv.shm.IncludeDir, srv.shm.ExportsDir, srv.shm.Exports = smbDir, nfsDir, filepath.Join(nfsDir, shares.DefaultExports)
+	rec := httptest.NewRecorder()
+	srv.ServeHTTP(rec, httptest.NewRequest("GET", "/shares", nil))
+	body := rec.Body.String()
+	for _, want := range []string{`id="external"`, "iso-pve", "/tank/iso/export/pve", "10.10.0.0/24(ro)", ">repoiso<"} {
+		if !strings.Contains(body, want) {
+			t.Errorf("shares page lacks %q", want)
+		}
+	}
+}