Bind citation metadata to the referenced source record

[Chumaniac]

An existing citation ID could point at the right source row while carrying an outdated digest or revision. Extend reference_exists with optional exact string-column bindings, and report mismatches or unavailable values using only declared metadata and CSV record positions.

Reuse the current bounded CSV inspection, unique target IDs and report formats. ID and metadata indexes share 100,000 cells and 64 MiB of hash-input capacity; tuple hashing is streamed with byte-length framing, and partial indexes are discarded on exhaustion. Existing contracts retain their normalized digest. Add an original synthetic example and document that matching local metadata does not fetch or authenticate source bytes.

Validation

• 643 tests passed; the existing opt-in Docker integration test remained skipped.
• Type checking, lint, build, package dry-run, changed Markdown target checks and whitespace checks passed.
• The built CLI accepted the synthetic matching catalog and rejected a changed revision without printing reference values.

The first package dry-run could not write the sandboxed user cache; rerunning with a task-local cache passed. No global permissions, dependencies, runtime capabilities, published packages or deployments changed. This feature requires the current source and is absent from the existing GitHub v0.1.7 release.

A whole-tree link inventory also found the two deliberately broken links in existing invalid fixtures; both fixtures were verified unchanged. The changed-document link audit and repository documentation regression passed.