fix(registry): allowlist error detail metadata

[bokelley]

Summary

• expose public typed RegistryErrorDetails and RegistryValidationIssue envelopes
• project only bounded machine-readable registry error fields while dropping remote prose, rejected values, credentials, and unknown nested data
• preserve bounded retry metadata and documented legacy recovery codes for authenticated write/feed workflows

Validation

• uv run pytest -q tests/test_registry.py tests/test_public_api.py (194 passed)
• make lint typecheck
• uv run pytest -q (7179 passed, 41 skipped, 9 deselected, 1 xfailed)
• commit hooks: Black, Ruff, mypy, adopter fixtures, Bandit, JSON/YAML and repository hygiene checks
• independent code and protocol/security expert reviews: approved

Refs #1031

[aao-secretariat]

Ladon verdict: Approve

Approve — no blocking or medium findings.

This PR replaces the raw-body RegistryError.details with a fail-closed allowlist projection in registry.py: only bounded machine tokens (code/field/ids/retry hints/valid_values/validation_issues) survive, while remote prose, rejected inputs, credentials, and secret-shaped codes are dropped, with per-list incremental budgets plus a final 4KB size backstop. Retry-hint parsing still reads the raw payload (registry.py:357), so retry behavior is unchanged. Change is well tested (secret leakage, prose rejection, legacy-code promotion, bounds).

Checks applied:

• No critical/high findings (row 1 clear).
• gated_paths: false, so row 2 does not apply despite review_decision: REVIEW_REQUIRED.
• high_risk: true is driven solely by src/adcp/__init__.py (modified), with no medium-or-higher finding on that file — row 5 does not fire; row 3 (deleted) and row 4 (medium data-loss/schema/infra) do not apply.
• No author no-auto-approve team match (row 7 clear).
• No prior decision.
• Only one finding, severity low, so row 8 (≥3 medium) does not apply.

Medium findings: none.

The single low finding (exceptions.py:198 — details narrows public content) is a deliberate, intended tightening consistent with the fail-closed security goal and is omitted per the low-severity policy. Falls through to row 9 — approve.