Batch of mechanical cleanups flagged in the prelaunch review: keepalive Timer+Reset -> Ticker; fail loudly on fs.Sub error; meaningful 500 messages with http.StatusInternalServerError; IdleTimeout on the public server (WriteTimeout deliberately omitted for SSE, now documented) and ReadHeaderTimeout on the admin listener; errors.New / strconv.FormatInt over fmt; CountMatches checks err before interpreting n; merged duplicate viewer doc comment; dropped no-op .Funcs; removed non-load-bearing cch drains; moved countResult next to its use in render.go. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>