feat: add subscriptions

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

crates/crunch-envelope/src/generated/crunch.envelope.rs

@@ -0,0 +1,18 @@
+#[derive(Clone, PartialEq, ::prost::Message)]
+pub struct Envelope {
+    #[prost(message, optional, tag="1")]
+    pub metadata: ::std::option::Option<Metadata>,
+    #[prost(bytes, tag="2")]
+    pub content: std::vec::Vec<u8>,
+}
+#[derive(Clone, PartialEq, ::prost::Message)]
+pub struct Metadata {
+    #[prost(string, tag="1")]
+    pub domain: std::string::String,
+    #[prost(string, tag="2")]
+    pub entity: std::string::String,
+    #[prost(uint64, tag="3")]
+    pub timestamp: u64,
+    #[prost(uint64, tag="4")]
+    pub sequence: u64,
+}

crates/crunch-envelope/src/generated/mod.rs

@@ -0,0 +1,3 @@
+pub mod crunch {
+    include!("crunch.envelope.rs");
+}