Normal pub/sub bypasses queue manager entirely

[dborovcanin]

Only topics prefixed with $queue/ route through the queue manager. Normal MQTT pub/sub (e.g. sensor/temp) goes through the topic router directly via distribute() in mqtt/broker/publish.go, never touching a queue. This creates two distinct routing paths — queue-backed and router-only, which means normal MQTT messages are invisible to AMQP consumers and vice versa.

We need to check if this design make sense or we should replace it with a more streamlined version where the routing is shared.