fix(client): address PR #7 review — ephemeral port, input drop docs

Hoshe #1: E2E test now uses random ephemeral port (49152-65535) with
port rotation on bind failure, avoiding conflicts in parallel CI.
Hoshe #2: Documented intentional input drop on encode failure in
SimBridge — re-queuing would retry bad data and server tick has
already advanced.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/sim_bridge.gd

@@ -130,7 +130,10 @@ func _process(delta: float) -> void:
 			while msg.size() > 0:
 				receive_bytes(msg)
 				msg = _bridge.poll_message()
-			# Send: batch-encode and flush outbound buffer as one frame (Vec<PlayerInput>)
+			# Send: batch-encode and flush outbound buffer as one frame (Vec<PlayerInput>).
+			# Inputs are drained before encoding. On encode failure the inputs are
+			# intentionally dropped — re-queuing would retry the same bad data and
+			# the server tick has already advanced, making stale inputs invalid.
 			var outbound := drain_outbound()
 			if outbound.size() > 0:
 				var encoded := Protocol.encode_player_inputs(outbound)
@@ -139,7 +142,7 @@ func _process(delta: float) -> void:
 					if err != OK:
 						push_error("SimBridge: failed to send message: %s" % error_string(err))
 				else:
-					push_error("SimBridge: failed to batch-encode %d inputs" % outbound.size())
+					push_error("SimBridge: failed to batch-encode %d inputs (dropped)" % outbound.size())
 		StreamPeerTCP.STATUS_CONNECTING:
 			pass  # Should not happen in CONNECTED state
 		StreamPeerTCP.STATUS_ERROR: