Move max payload validation from the parser to ProcessPubAsync so the
server sends -ERR 'Maximum Payload Violation' and closes the connection
(matching Go reference client.go:2442). In pedantic mode, reject PUB
with wildcard subjects via -ERR 'Invalid Publish Subject' (client.go:2869).
Add disposed guard to SubList.Remove to prevent crash during shutdown.
Replace empty catch blocks with meaningful log statements in NatsServer,
NatsClient, and Program. Add WaitForReadyAsync() to NatsServer for
deterministic server startup. Replace Task.Delay/Thread.Sleep in tests
with PING/PONG protocol flush and SubscribeCoreAsync for reliable
subscription synchronization.
Add NatsParser that reads NATS protocol commands from
ReadOnlySequence<byte>. Identifies commands by first 2 bytes using
case-insensitive bit masking. Handles PUB/HPUB payload reading with
stateful _awaitingPayload for split-packet scenarios. Uses Span<Range>
for zero-allocation argument splitting and ParseSize for ASCII decimal
parsing. Includes CommandType enum, ParsedCommand struct, and
ProtocolViolationException.
14 tests covering PING, PONG, CONNECT, INFO, SUB (with/without queue),
UNSUB (with/without max), PUB (with/without reply, zero payload),
HPUB, multiple commands, and case insensitivity.
