feat: machine status page, speed test, live presence, forwards without ufw (0.0.5)

Status page per machine: CPU load, RAM and disk of the client, sampled
by the agent only while the page is open and visible (one reading
serves every open tab), plus a button that has the agent measure its
link to the host: ping, down and up.

Online/offline now comes from the control polls the hub holds open, so
a dropped agent shows offline at once instead of 45 s later, and the
dashboard keeps the status column live.

A forward rule can be created "without ufw": the panel opens nothing in
ufw for it and so revokes nothing when it is deleted. The checkbox is
shown only while the ufw integration is on.

Dashboard row actions are icons; a status action is added.

internal/server/db.go

@@ -105,6 +105,7 @@ CREATE TABLE IF NOT EXISTS forward_rules (
 		`ALTER TABLE ufw_rules ADD COLUMN rule_id INTEGER NOT NULL DEFAULT 0`,
 		`ALTER TABLE agents ADD COLUMN run_user TEXT NOT NULL DEFAULT ''`,
 		`ALTER TABLE agents ADD COLUMN login_user TEXT NOT NULL DEFAULT ''`,
+		`ALTER TABLE forward_rules ADD COLUMN no_ufw INTEGER NOT NULL DEFAULT 0`,
 	} {
 		if _, err := db.sql.Exec(alter); err != nil && !strings.Contains(err.Error(), "duplicate column") {
 			return err
@@ -238,8 +239,9 @@ func (a Agent) TerminalUser() string {
 	return firstNonEmpty(a.LoginUser, a.RunUser, "root")
 }
 
-// Online reports whether the agent polled recently enough to be considered up.
-func (a Agent) Online() bool {
+// recentlySeen is the fallback for "online" right after a server start, while
+// the hub has not seen the agents' polls yet (see Server.online).
+func (a Agent) recentlySeen() bool {
 	return time.Since(a.LastSeen) < 45*time.Second
 }
 
@@ -327,6 +329,7 @@ type ForwardRule struct {
 	HostPort   int
 	ListenAddr string
 	Proto      string
+	NoUfw      bool // the panel opens no ufw rule for this forward
 }
 
 func (db *DB) CreateForwardRule(r ForwardRule) (int64, error) {
@@ -334,9 +337,9 @@ func (db *DB) CreateForwardRule(r ForwardRule) (int64, error) {
 		r.Proto = "http"
 	}
 	res, err := db.sql.Exec(
-		`INSERT INTO forward_rules(agent_id, client_port, host_port, listen_addr, proto, created_at)
-		 VALUES(?, ?, ?, ?, ?, ?)`,
-		r.AgentID, r.ClientPort, r.HostPort, r.ListenAddr, r.Proto, time.Now().Unix())
+		`INSERT INTO forward_rules(agent_id, client_port, host_port, listen_addr, proto, no_ufw, created_at)
+		 VALUES(?, ?, ?, ?, ?, ?, ?)`,
+		r.AgentID, r.ClientPort, r.HostPort, r.ListenAddr, r.Proto, r.NoUfw, time.Now().Unix())
 	if err != nil {
 		return 0, err
 	}
@@ -345,7 +348,7 @@ func (db *DB) CreateForwardRule(r ForwardRule) (int64, error) {
 
 func (db *DB) ListForwardRules() ([]ForwardRule, error) {
 	rows, err := db.sql.Query(
-		`SELECT id, agent_id, client_port, host_port, listen_addr, proto FROM forward_rules ORDER BY id`)
+		`SELECT id, agent_id, client_port, host_port, listen_addr, proto, no_ufw FROM forward_rules ORDER BY id`)
 	if err != nil {
 		return nil, err
 	}
@@ -353,7 +356,7 @@ func (db *DB) ListForwardRules() ([]ForwardRule, error) {
 	var out []ForwardRule
 	for rows.Next() {
 		var r ForwardRule
-		if err := rows.Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto); err != nil {
+		if err := rows.Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto, &r.NoUfw); err != nil {
 			return nil, err
 		}
 		out = append(out, r)
@@ -378,8 +381,8 @@ func (db *DB) ListForwardRulesByAgent(agentID string) ([]ForwardRule, error) {
 func (db *DB) GetForwardRule(id int64) (*ForwardRule, error) {
 	r := &ForwardRule{}
 	err := db.sql.QueryRow(
-		`SELECT id, agent_id, client_port, host_port, listen_addr, proto FROM forward_rules WHERE id = ?`, id).
-		Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto)
+		`SELECT id, agent_id, client_port, host_port, listen_addr, proto, no_ufw FROM forward_rules WHERE id = ?`, id).
+		Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto, &r.NoUfw)
 	if err == sql.ErrNoRows {
 		return nil, nil
 	}