initialize spec macro and standards

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

kaptan-spec/tests/ui/fail_missing_sidecar.rs

@@ -0,0 +1,8 @@
+use kaptan_spec::spec;
+
+#[spec("fail_missing_sidecar.v0.1.0.spec.md")]
+struct MissingSpec;
+
+fn main() {
+    let _ = core::mem::size_of::<MissingSpec>();
+}

kaptan-spec/tests/ui/fail_missing_sidecar.stderr

@@ -0,0 +1,5 @@
+error: couldn't read `$DIR/tests/ui/fail_missing_sidecar.v0.1.0.spec.md`: No such file or directory (os error 2)
+ --> tests/ui/fail_missing_sidecar.rs:3:1
+  |
+3 | #[spec("fail_missing_sidecar.v0.1.0.spec.md")]
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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);
+}

kaptan-spec/tests/ui/flight_core_contract.v0.1.0.spec.md

@@ -0,0 +1,10 @@
+---
+title: Flight core contract
+status: in-progress
+owners:
+  - Test Name <name@test.com>
+---
+
+# Summary
+
+Minimal spec for compile-time linkage testing.