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/.fingerprint/serde-5d64217da642452c/lib-serde.json

@@ -0,0 +1 @@
+{"rustc":11835527281324007204,"features":"[\"default\", \"derive\", \"serde_derive\", \"std\"]","declared_features":"[\"alloc\", \"default\", \"derive\", \"rc\", \"serde_derive\", \"std\", \"unstable\"]","target":11327258112168116673,"profile":2579911162000070427,"path":16120815544645295683,"deps":[[6557439603276904804,"build_script_build",false,369931326335128302],[11029742160753049355,"serde_core",false,9186085954047428496],[13312204359551525516,"serde_derive",false,11759028012438362215]],"local":[{"CheckDepInfo":{"dep_info":"debug/.fingerprint/serde-5d64217da642452c/dep-lib-serde","checksum":false}}],"rustflags":[],"config":9396254390672932401,"compile_kind":0}