Ech0's RSS feed renders unescaped tag names and raw-HTML markdown, stored XSS against subscribers

Summary The public RSS/Atom feed at /rss renders two attacker-controlled surfaces without HTML escaping. Tag names flow through fmt.AppendfrenderedContent, "%s", tag.Name at internal/service/common/common.go:120, and the Markdown renderer at internal/util/md/md.go does not set the html.SkipHTML...