teststation listens with quic-go's 30 s idle timeout; the live station uses 300 s #62

Purpose (reliability): a test that dials macula-go's in-process teststation sees the connection lifetime a live station gives, so a test passes or fails for the reasons production would; today a 30 s path outage ends the connection in tests and not on the fleet.

Facts (v0.27.0-rc.4 and origin/master)

• teststation/station.go:161 listens with &quic.Config{}: quic-go's default MaxIdleTimeout is 30 s.
• The idle timeout in force is the minimum of both sides'. Clients ask for 300 s (macula-rust transport.rs IDLE_TIMEOUT, macula-go transport/profile_dial.go:192), and the live Erlang station listens with 300 s (macula_quic.erl, idle_timeout_ms default 300_000). So against the teststation every client gets 30 s.
• Seen in A publication made while a link cannot carry packets is destroyed, and nothing above the transport is told macula-rust#57: a 30 s black hole ends the link at the teststation's 30 s (Io("timed out")) and the test fails. The same test with the teststation set to MaxIdleTimeout: 300s, KeepAlivePeriod: 15s passes.

Done when

The teststation listens with the live station's idle timeout and keep-alive (300 s / 15 s), named once, and a test pins it.