feat(checker): examples() and spec_files() carry the specification's files

A consumer of the checker crate needs no path into this repository.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

target/debug/build/serde-2b4970e64ce601f3/out/private.rs

@@ -0,0 +1,6 @@
+#[doc(hidden)]
+pub mod __private229 {
+    #[doc(hidden)]
+    pub use crate::private::*;
+}
+use serde_core::__private229 as serde_core_private;