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-2b4970e64ce601f3/run-build-script-build-script-build

@@ -0,0 +1 @@
+ee927ed194422205

target/debug/.fingerprint/serde-2b4970e64ce601f3/run-build-script-build-script-build.json

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+{"rustc":11835527281324007204,"features":"","declared_features":"","target":0,"profile":0,"path":0,"deps":[[6557439603276904804,"build_script_build",false,16383222238764792476]],"local":[{"RerunIfChanged":{"output":"debug/build/serde-2b4970e64ce601f3/output","paths":["build.rs"]}}],"rustflags":[],"config":0,"compile_kind":0}