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/bookspec-checker-2a3f2963ec68cc71/invoked.timestamp

@@ -0,0 +1 @@
+This file has an mtime of when this was started.

target/debug/.fingerprint/bookspec-checker-2a3f2963ec68cc71/test-lib-bookspec_checker

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+0da6e62fc71ddedf

target/debug/.fingerprint/bookspec-checker-2a3f2963ec68cc71/test-lib-bookspec_checker.json

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+{"rustc":11835527281324007204,"features":"[]","declared_features":"[]","target":16169830567703704039,"profile":8811090623648874550,"path":4002775004783543747,"deps":[[4551433501944786770,"toml",false,15374768485179113397],[6557439603276904804,"serde",false,6892974117134619325],[8160210889872729633,"serde_json",false,3272240903266352360],[13045287708915633801,"rust_decimal",false,11170346456977673264],[16117757646811882223,"chrono",false,10331829653311224801],[16226840668845106605,"include_dir",false,740751514412257382]],"local":[{"CheckDepInfo":{"dep_info":"debug/.fingerprint/bookspec-checker-2a3f2963ec68cc71/dep-test-lib-bookspec_checker","checksum":false}}],"rustflags":[],"config":9396254390672932401,"compile_kind":0}