fix(client): address PR #4 round 2 review feedback

- decode_snapshot() reports dropped entities via push_error and returns
  decode_errors count so callers can detect partial data (D-010
  information boundary compliance)
- receive_bytes() warns when overwriting unconsumed snapshot, documents
  latest-wins semantics
- Rename misleading test to test_encode_produces_nonempty_bytes
- Fix tick rate comment: 10 ticks/game-minute per D-031

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

client/scripts/protocol/protocol.gd

@@ -26,17 +26,25 @@ static func decode_snapshot(bytes: PackedByteArray) -> Variant:
 		return null
 
 	var entities: Array[Dictionary] = []
-	for raw_entity in raw["entities"]:
+	var raw_entities: Array = raw["entities"]
+	var dropped := 0
+	for raw_entity in raw_entities:
 		var entity = _decode_entity(raw_entity)
 		if entity != null:
 			entities.append(entity)
+		else:
+			dropped += 1
+
+	if dropped > 0:
+		push_error("Protocol: %d/%d entities failed to decode (D-010 information boundary violation)" % [dropped, raw_entities.size()])
 
 	# GDScript int is signed 64-bit. Rust tick is u64 but will not exceed 2^63
-	# in any realistic scenario (would require ~29 billion years at 10 ticks/min).
+	# in any realistic scenario (would require ~29 billion years at 10 ticks/game-minute per D-031).
 	var tick: int = raw["tick"]
 	return {
 		"tick": tick,
 		"entities": entities,
+		"decode_errors": dropped,
 	}