fix(train): the firmware relay's calls to Polar time out, are bounded and limited per person (ADR 0030, D55)

Like BRouter's and Photon's: timeouts on connecting and reading, a check answer up to 64 KB and a file up to 64 MB, no redirect but to https, one fetch per file at a time, and 10 checks and downloads a minute for a person (tooOften). An answer that names no update properly is unreachable, no longer no update. The relay is the pod's, as routing's and search's.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/train/halkyon_train_client/lib/src/protocol/firmware/loop_firmware_refused.dart

@@ -15,7 +15,9 @@ import 'package:serverpod_client/serverpod_client.dart' as _isc;
 /// Why the instance relays no firmware (ADR 0030, D40): `off` where its
 /// operator turned relaying off, `invalid` for a band's figures it doesn't
 /// take, `unknown` for a file it wasn't told of (or no longer holds),
-/// `unreachable` where Polar's service didn't answer.
+/// `unreachable` where Polar's service didn't answer or answered with
+/// something else than an update, `tooOften` beyond 10 checks and
+/// downloads a minute for a person (D55).
 abstract class LoopFirmwareRefused
     implements
         _isc.SerializableException,