Integrate Diagnostic Triage as a pinned consumer

[Anionix]

Canonical implementation: Anionix/diagnostic-triage#1

CI observation/performance lane: #400

Goal

Integrate data-format-lab as the first pinned consumer of the standalone
Diagnostic Triage CLI. This repository owns only repository policy,
configuration, integration fixtures, observation workflow, and immutable
source/Nix pins.

Completed

• Pin standalone revision through Nix without changing the repository's
  existing Nixpkgs or Rust overlay revisions (Pin the standalone Diagnostic Triage flake input #429), then advance atomically to
  Linux-package fix
  d036a33bfc5a49c05f54200df9be8f55e2987cd6 (Pin Diagnostic Triage Linux package fix #431).
• Add diagnostic-triage.toml, repository integration fixtures, and a
  separate observe-only workflow (Consume pinned Diagnostic Triage in observation CI #430).
• Verify source attribution, exit/verdict mapping, malformed configuration,
  missing Provider, offline GitHub Actions observation, and tracked-tree
  immutability.
• Remove the divergent local generic taxonomy, schema, and local-copy
  contract test in the same passing consumer transition (Consume pinned Diagnostic Triage in observation CI #430).
• Keep policy failure non-blocking during observation while rejecting
  operational exit code 2 and mismatched reports.
• Remove the obsolete local check-jsonschema dependency and its orphaned
  transitive lock entries (Remove obsolete local schema validator dependency #432).

Remaining

• Complete the observation phase for at least 14 days and 20 successful
  runs.
• Complete the warning phase separately for at least 14 days and 20
  successful runs.
• Confirm incomplete rate at most 1%, blocking-candidate false-positive
  rate at most 2%, and zero unauthorized writes before blocking rollout.

Acceptance

• check and ci leave the tracked tree unchanged.
• Exit codes remain 0 pass, 1 policy failure, and 2
  operational/config/protocol failure.
• Generic defects are tracked only in Anionix/diagnostic-triage;
  repository-specific defects remain bug Issues here.
• Consumer tests use the pinned standalone contracts offline and normal CI
  performs no runtime schema network fetch.

[Anionix]

Consumer rollout update:

• CI observability slice merged in Expose CI smoke lanes as native parallel steps #433.
• Native parallel observation 1/20 is recorded in Split long CI lanes into observable parallel jobs #400 with independent pytest/fair/claims/prompt/equivalence durations.
• Late merged-review defects were classified and fixed:
  • consumer source-identity contamination: Keep Diagnostic Triage evidence outside checkout identity #434 → Keep Diagnostic Triage evidence outside checkout identity #435
  • standalone implicit flake.lock mutation: Reject implicit flake.lock updates in package CI diagnostic-triage#298 → Reject implicit flake.lock updates in package CI diagnostic-triage#299
• Source review threads were replied to and resolved after merge.
• Full merged-PR sweeps now report zero current unresolved/non-outdated review threads in both repositories.

The tracker remains open for the remaining observation/warning time and run-count gates.