Field sensor readiness branch (larger; not the claim-hygiene slice)

[coreytshaffer]

Align Clear Lake Watch reviewer-facing freshness claims with current validation behavior.

The validators currently surface stale-data warnings and require manual review before republish; they do not implement automated stale-data blocking or an -AllowStaleSnapshot override gate. This slice updates the safety-case and publication docs to avoid overclaiming fail-closed behavior, removes hardcoded snapshot-age text that had drifted, fixes the PowerShell validator's day-count guards, and adds follow-up backlog items.

Changes

• Safety-case wording (docs/epistemic_safety_case.md): stale data now described as warn + manual review, not "fail closed"; boundary table gains a "Status Today" column marking unimplemented behaviors.
• Phantom flag (epistemic_safety_case.md, deployment.md, flagship-maturity-plan.md, publication-review-checklist.md, public-mirror-boundary.md): every -AllowStaleSnapshot reference now states it is proposed / not implemented and that staleness is a manual reviewer decision.
• Rotting age text (public-snapshot-release-note-2026-05-13.md, reviewer-demo-notes.md): removed hardcoded "23 days old" cues; point reviewers to the dashboard's dynamically computed snapshot-age badge.
• Validator drift (scripts/validate-public-mirror.ps1): replaced hardcoded "27 days old" guards with a durable "snapshot-age badge" check, so the README's documented local validation command is green again.
• Backlog (docs/public-backlog.md): added follow-ups for a real stale-snapshot publication gate, a stale-source fail-vs-warn decision, Python/PowerShell validator unification, and computed source/weather stale status.

Validation

• python scripts/validate-public-mirror.py → PASS (exit 0)
• pwsh ./scripts/validate-public-mirror.ps1 → PASS (exit 0; was failing before on the day-count guards)
• Remaining output is the intentional staleness warnings (snapshot age, FHABS source ages), which are the trust signals this slice preserves.

Docs/claim-hygiene only — no dashboard feature or data-publication changes.

🤖 Generated with Claude Code

[coreytshaffer]

Superseded for the narrow claim-hygiene slice by #37, which re-expresses only the snapshot-age / validator claim-hygiene against current main as a small, conflict-free PR.

This PR (#36) is intentionally left open as the larger field-sensor-readiness branch for later work. It is not a clean single-thesis change: it is 7 commits diverged from main and currently CONFLICTING, because the branch and main independently built overlapping public-mirror validation pipelines. Do not squash-merge it as-is under a claim-hygiene title. When it is picked back up, reconcile it against main first and give it an accurate, broadened description.