Initial import: nasmon health monitor, split out of home_nas

Go service (nasmon/) plus nfpm packaging (packaging/), carried over from
the home_nas monorepo. Adds rpm packaging alongside the existing deb
build (Fedora/RHEL/Rocky dependency names via nfpm overrides, per-format
systemd unit path, dpkg+rpm-compatible maintainer scripts) and a Gitea
Actions workflow that builds both formats on every push.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/collect/services.go

@@ -0,0 +1,58 @@
+package collect
+
+import (
+	"encoding/json"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+// ShareServices is the read-only view of the file-sharing daemons.
+type ShareServices struct {
+	SMBInstalled bool `json:"smb_installed"`
+	NFSInstalled bool `json:"nfs_installed"`
+	SMBActive    bool `json:"smb_active"`
+	NFSActive    bool `json:"nfs_active"`
+	SMBSessions  int  `json:"smb_sessions"`
+}
+
+// ReadShareServices checks which sharing daemons exist and run.
+func ReadShareServices() ShareServices {
+	var s ShareServices
+	if _, err := exec.LookPath("smbd"); err == nil {
+		s.SMBInstalled = true
+		s.SMBActive = unitActive("smbd")
+		if s.SMBActive {
+			s.SMBSessions = smbSessions()
+		}
+	}
+	if _, err := exec.LookPath("exportfs"); err == nil {
+		s.NFSInstalled = true
+		s.NFSActive = unitActive("nfs-server")
+	}
+	return s
+}
+
+func unitActive(unit string) bool {
+	out, _ := run(5*time.Second, "systemctl", "is-active", unit)
+	return strings.TrimSpace(string(out)) == "active"
+}
+
+// smbSessions counts connected SMB sessions via smbstatus --json (Samba ≥ 4.17).
+func smbSessions() int {
+	out, err := run(10*time.Second, "smbstatus", "--json", "-b")
+	if err != nil && len(out) == 0 {
+		return 0
+	}
+	return parseSmbSessions(out)
+}
+
+func parseSmbSessions(b []byte) int {
+	var j struct {
+		Sessions map[string]json.RawMessage `json:"sessions"`
+	}
+	if json.Unmarshal(b, &j) != nil {
+		return 0
+	}
+	return len(j.Sessions)
+}