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/toml_parser-b2d815c555e46f3d/lib-toml_parser.json

@@ -0,0 +1 @@
+{"rustc":11835527281324007204,"features":"[\"alloc\", \"std\"]","declared_features":"[\"alloc\", \"debug\", \"default\", \"simd\", \"std\", \"unsafe\"]","target":1950419911817058027,"profile":2552771414129367892,"path":5536876969299381742,"deps":[[6338624599557368326,"winnow",false,3189460172750420749]],"local":[{"CheckDepInfo":{"dep_info":"debug/.fingerprint/toml_parser-b2d815c555e46f3d/dep-lib-toml_parser","checksum":false}}],"rustflags":[],"config":9396254390672932401,"compile_kind":0}