v0.12.0

Added

• Added the independent a3s.test.remote-artifacts/1 protocol with generated
  strict schemas for service inspection, bounded terminal-report queries,
  paginated artifact descriptors, and chunked report or evidence reads.
• Added a3s-test worker artifacts schema and authenticated
  POST /v1/artifacts support to the loopback reference host. Readiness now
  reports both execution and artifact descriptors.
• Added deployment-owned two-tier retention. Complete inputs, reports, and
  evidence are bounded by job count, aggregate bytes, and age; compact report
  indexes have independent longer count and age windows. Age limits continue
  to run while the worker is idle.
• Added restart reconstruction, crash-recoverable retained to pruning to
  pruned transitions, and bounded full-index garbage collection.

Safety

• Artifact lists and reads bind job ID, dispatch ID, immutable request digest,
  and canonical bounded cursors. Reads additionally bind the artifact SHA-256,
  exact indexed path, offset, and maximum chunk size.
• Artifact scans and reads reject symbolic links, Windows reparse points,
  containment escapes, non-regular or empty evidence, ASCII case-folded path
  collisions, file replacement, digest drift, oversized trees, and corrupted
  persisted indexes.
• Unsafe evidence cannot leave a successful terminal result. The worker
  records a durable failure, removes only the owned payload, preserves any
  external link target, and fails closed to new submissions if durable
  retention becomes unhealthy.

Changed

• Raised the Rust workspace release to 0.12.0. The unchanged Test Kit remains
  0.2.0.
• Kept artifact transport out of a3s.test.remote-worker/1; execution and
  retained-byte access remain independently versioned authority boundaries.