v0.16.0

Added

• OutputMode enum (Human, Json, Yaml, Quiet, Porcelain) and
  OutputEmitter struct in aqueduct-cli::output; global --quiet and
  --porcelain flags are now routed through the emitter (ERG-1, M11).
• serde_yaml workspace dependency; YAML output in plan, status, and diff
  subcommands now uses serde_yaml::to_string instead of hand-rolled format strings,
  correctly escaping quotes, colons, and newlines (ERG-3).
• just gen-docs recipe that regenerates docs/api-reference.md from
  aqueduct --help output; stale references to --patroni-endpoint, --timeout,
  --lock-timeout, and --no-cost removed (ERG-4, M3).
• Binary CLI tests (assert_cmd) for every subcommand's exit codes and --help
  output: quiet_suppresses_decorative_output, porcelain_outputs_key_value_only,
  yaml_escapes_quotes_and_newlines, plan_help_documents_fail_if_changed,
  apply_help_documents_dry_run, status_help_documents_fail_on_drift,
  diff_help_documents_fail_on_drift, destroy_help_documents_dry_run,
  rollback_help_documents_dry_run, plan_missing_dsn_exits_2,
  validate_exits_0_on_valid_files, validate_differential_ivm_unsupportable_fails,
  validate_format_json_produces_valid_json, version_flag_outputs_semver (TEST-2).
• --poll-interval flag on aqueduct status (PERF-2).
• Spec-hash caching in status --watch: migration files are only reloaded when any
  .sql mtime changes; live state always polled fresh (PERF-2).
• postgres_version_matrix_min_supported integration test verifying the full
  create/apply/status cycle on PostgreSQL 18+ (H10).
• CONTRIBUTING.md documenting Docker/Testcontainers prerequisites, just recipes,
  integration test environment variables, PG version matrix, coding standards, and
  a step-by-step guide for adding cookbook recipes.

Changed

• fmt::format_migration now returns Result<Option<String>> and propagates IO
  errors; aqueduct fmt prints a diagnostic when a file cannot be read instead of
  silently treating it as empty (L2).
• CANONICAL_KEY_ORDER constant in aqueduct-core::fmt renamed to
  KNOWN_FRONTMATTER_KEYS to reflect its actual role (L3).
• TestDb::connection_string field visibility narrowed from pub to pub(crate)
  to prevent external crates from depending on the internal representation (L14).
• docs/security.md: AWS, GCP, and Vault secret backend rows updated from
  "Planned (v0.12)" to "Implemented"; injected SQL trust-boundary note updated to
  describe the CatalogSchema newtype introduced in v0.14.
• docs/api-reference.md regenerated from aqueduct --help output.

Fixed

• aqueduct status --format yaml now produces valid YAML that passes
  serde_yaml::from_str round-trip including special characters.
• aqueduct plan --format yaml correctly escapes project names containing
  quotes, colons, and newlines.