Polling Consumer Generator

[GeneratePollingConsumer] creates a typed PollingConsumer<TPayload> factory.

[GeneratePollingConsumer(typeof(ReplenishmentRequest), FactoryName = "Create", ConsumerName = "warehouse-replenishment-poller")]
public static partial class WarehousePoller
{
    [PollingConsumerSource]
    private static Message<ReplenishmentRequest>? Poll(MessageContext context) => TryReadNext();
}

The source method must be static, return Message<TPayload>?, and accept a MessageContext.

Diagnostics:

• PKPOLL001: host type must be partial.
• PKPOLL002: exactly one polling source is required.
• PKPOLL003: polling source signature is invalid.