feat(checks): name the rc.4 rules a validator can enforce

[simontaurus]

OOLD-SCH-96a3 and OOLD-EXT-c77a are marked machine-checkable in the catalogue and had no check behind them. coverage.rules therefore reported the root @context requirement, the breaking change rc.4 led with, as unenforced: the meta-schema rejects a document without one, but nothing attributed that to the rule.

Checks

rule.context for OOLD-SCH-96a3. The rule is presence, not content, so the check reflects that:

no @context          -> flagged
@context: {}         -> ok
@context: "Thing.schema.json"  -> ok

rule.range-form for OOLD-EXT-c77a, walking nested subschemas:

IRI / array of IRIs / subschema -> ok
42 / ["A", 7]                   -> flagged

Both ids drop out of the coverage.rules warning when validating the specification's examples/.

OOLD-SCH-cfb8 is not covered here: it constrains OO-LD's own vocabulary rather than any document, and was reclassified machine_checkable=no in 1.0.0-rc.5. OOLD-INS-770a needs the context view to decide whether a term carries @type: "@id", so it is left for the conformance work.

522 passed, 7 skipped.

[github-actions]

Release preview

Merging this PR would release v2.1.0 (current: v2.0.0).

Changelog preview (truncated)

## v2.1.0 (2026-09-27)

### Features

- **checks**: Name the rc.4 rules a validator can enforce
  ([`882cfd1`](https://github.com/OO-LD/oold-python/commit/882cfd1b7c49aa92f4cd87c598c98679294d40f2))

_{Preview via python-semantic-release and conventional commits.}

[github-actions]

📊 Benchmark Results

Click to see benchmark comparison

📊 Benchmark Comparison (threshold: 1.3x)
============================================================

➖ Unchanged (within threshold):
  ➖ test_simple_dict_document_store: 0.0015s → 0.0015s (-0.1%)
  ➖ test_sqlite_document_store: 0.0016s → 0.0016s (-0.7%)
  ➖ test_local_sparql_store: 0.0292s → 0.0285s (-2.1%)
  ➖ test_oneof_subschema: 0.0460s → 0.0469s (+2.1%)
  ➖ test_enum_docstrings: 0.0387s → 0.0439s (+13.4%)
  ➖ test_subclass_inheritance: 0.0427s → 0.0415s (-2.7%)
  ➖ test_class_hierarchy: 0.0391s → 0.0389s (-0.7%)
  ➖ test_core[v1]: 0.0285s → 0.0291s (+2.3%)
  ➖ test_core[v2]: 0.0330s → 0.0328s (-0.6%)
  ➖ test_schema_generation[v1]: 0.0014s → 0.0014s (-0.9%)
  ➖ test_schema_generation[v2]: 0.0029s → 0.0029s (-0.9%)
  ➖ test_simple_json: 0.0005s → 0.0005s (-2.0%)
  ➖ test_complex_graph: 0.0011s → 0.0011s (-0.6%)

============================================================
Summary: 0 regressions, 0 improvements, 13 unchanged
============================================================

✅ No significant performance regressions

Threshold: 1.3x (30% slower triggers a regression warning)

Note: Benchmarks are informational only and won't fail the build.

_{💡 Tip: Download the benchmark-results artifact for detailed JSON data}

[codecov]

Codecov Report

❌ Patch coverage is 91.30435% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/oold/validation/check_registry.py	91.3%	1 Missing and 1 partial ⚠️

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