N-03 / H-28 CANONICAL PINNED-DIAGNOSTICS JSON ORACLE

File under test:
Day060_H20_Fixture_Pinned_Diagnostics.json

Canonical-form obligations from W002-HELP-001.8:
- UTF-8 without BOM
- exactly two top-level fields: registry_version, diagnostics
- registry_version is string "1"
- diagnostics sorted by ascending UTF-8 byte order of diagnostic_id
- every diagnostic entry has exactly seven fields:
  diagnostic_id
  severity
  phase
  behavior
  next_action
  required_facts
  optional_facts
- required_facts sorted by ascending UTF-8 byte order, unique
- optional_facts sorted by ascending UTF-8 byte order, unique
- required_facts and optional_facts disjoint
- diagnostic IDs unique

H-28 scope:
- 28 fixture-pinned diagnostics, including DS-MAT-017 from H-26.
- explanatory meanings remain in the PRD tables, not as extra JSON registry fields.
