Replace all log.Println/log.Printf calls across follow.go, star.go, reaction.go, gfi.go, and profile.go with s.logger.Error/Warn/Info using structured key-value pairs. Each handler opens with a child logger via s.logger.With("handler", "FuncName"). Firehose-idempotent delete failures (follow, star, reaction) use Warn; all other failures use Error. Signed-off-by: Matías Insaurralde <matias@insaurral.de>