feat: with base envelope

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

crates/crunch-envelope/build.rs

@@ -0,0 +1,10 @@
+extern crate capnpc;
+
+fn main() {
+    capnpc::CompilerCommand::new()
+        .output_path("src/")
+        .src_prefix("schemas/")
+        .file("schemas/envelope.capnp")
+        .run()
+        .unwrap();
+}