initialize spec macro and standards

Signed-off-by: Onur Özkan <work@onurozkan.dev>

kaptan-spec/tests/ui/flight_core_contract.rs

@@ -0,0 +1,9 @@
+use kaptan_spec::spec;
+
+#[spec("flight_core_contract.v0.1.0.spec.md")]
+struct FlightCore;
+
+fn main() {
+    let size = core::mem::size_of::<FlightCore>();
+    assert_eq!(size, 0);
+}