v0.5.1 — Machine-readable conformance and compatibility catalogs

Added

• specification/v0.4/conformance-rules.json: machine-readable catalog that
  assigns a stable identifier to every MUST/MUST NOT/SHOULD obligation in the
  v0.4 conformance document: producer rules AIOS-0.4-P01–P12,
  external-reference rules X01–X02, consumer rules C01–C04, D-004
  closed-vocabulary rules U01–U02, extension naming E01, draft
  self-description D01, and claim format K01. Each rule quotes its
  normative sentence and says whether schema validation, semantic checks, or
  only a process obligation can decide it.
• specification/v0.5/compatibility.json: the spec_version marker grammar,
  the schema set published behind each marker (0.4-draft today), and
  identifiers AIOS-0.5-V01–V06 for each row of the consumer compatibility
  table.
• tests/test_conformance_catalogs.py: fails if either catalog drifts from
  the normative Markdown it mirrors.

Notes

• The Markdown documents remain normative; the catalogs only label what they
  already require. No schema, vocabulary, or milestone status changed.
• Released as a patch on the v0.5 line (v0.5.1) because it labels existing
  rules rather than adding normative content.