feat: add subscriptions

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/crunch-traits/src/transport.rs

@@ -0,0 +1,12 @@
+use std::sync::Arc;
+
+use async_trait::async_trait;
+
+use crate::{errors::TransportError, EventInfo};
+
+#[async_trait]
+pub trait Transport {
+    async fn publish(&self, event_info: &EventInfo, content: Vec<u8>)
+        -> Result<(), TransportError>;
+}
+pub type DynTransport = Arc<dyn Transport + Send + Sync + 'static>;