feat(channels): include event verb in ntfy title + smtp subject

Raise / ack / resolve all rendered with the same title and body on
ntfy and SMTP, so a recovery looked identical to the original alert.
Webhook was already fine because the JSON envelope carries 'event'.

ntfy:
  Title  '[raised · warning] dev backup_failed' (was '[warning] …')
  Tags   'raised,warning,backup_failed' (was 'warning,backup_failed')
  Body   'Resolved · <message>' / 'Acknowledged · <message>' on those events
SMTP:
  Subject '[restic-manager] [raised · warning] dev: backup_failed'

Plus: cmd/_fake_alert now accepts the ref as a positional argument
(go run ./cmd/_fake_alert steve-001) instead of silently ignoring
unknown positional args. Refuses ambiguous '-ref X positional Y'.

internal/notification/ntfy.go

@@ -58,14 +58,34 @@ func (c *NtfyChannel) Send(ctx context.Context, p Payload) (int, time.Duration,
 	server := strings.TrimRight(c.cfg.ServerURL, "/")
 	url := server + "/" + c.cfg.Topic
 
-	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBufferString(p.Message))
+	// Body carries the event verb so the body alone is unambiguous when
+	// it shows up on a phone lockscreen without the title.
+	body := p.Message
+	switch p.Event {
+	case EventResolved:
+		body = "Resolved · " + p.Message
+	case EventAcknowledged:
+		body = "Acknowledged · " + p.Message
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBufferString(body))
 	if err != nil {
 		return 0, 0, fmt.Errorf("ntfy: build request: %w", err)
 	}
 
+	// Title prefix tracks the event so raise vs ack vs resolve are
+	// visually distinct in the ntfy notification list.
+	verb := "raised"
+	switch p.Event {
+	case EventAcknowledged:
+		verb = "ack"
+	case EventResolved:
+		verb = "resolved"
+	case EventTest:
+		verb = "test"
+	}
 	req.Header.Set("Content-Type", "text/plain")
-	req.Header.Set("Title", fmt.Sprintf("[%s] %s %s", p.Severity, p.HostName, p.Kind))
-	req.Header.Set("Tags", p.Severity+","+p.Kind)
+	req.Header.Set("Title", fmt.Sprintf("[%s · %s] %s %s", verb, p.Severity, p.HostName, p.Kind))
+	req.Header.Set("Tags", verb+","+p.Severity+","+p.Kind)
 	req.Header.Set("Priority", priorityForSeverity(p.Severity, c.defaultPriority))
 	if p.Link != "" {
 		req.Header.Set("Click", p.Link)