refactor(frontend): move form-item hints from extra to tooltip

Switch reality target, node options, and WARP auto-update-IP hints from
inline extra text to label tooltips for a cleaner form layout.

internal/web/service/email/email.go

@@ -270,7 +270,7 @@ func parseRecipients(toStr string) []string {
 		return nil
 	}
 	var out []string
-	for _, s := range strings.Split(toStr, ",") {
+	for s := range strings.SplitSeq(toStr, ",") {
 		s = strings.TrimSpace(s)
 		if s != "" {
 			out = append(out, s)

internal/web/service/email/subscriber.go

@@ -53,7 +53,7 @@ func (s *Subscriber) isEventEnabled(t eventbus.EventType) bool {
 	if err != nil || events == "" {
 		return false
 	}
-	for _, e := range strings.Split(events, ",") {
+	for e := range strings.SplitSeq(events, ",") {
 		if strings.TrimSpace(e) == string(t) {
 			return true
 		}