Add reviewed stale-source rehearsal mode for formal refresh workflow

[coreytshaffer]

Summary

Adds an explicit review-only stale-source rehearsal path to the manual formal refresh workflow without weakening the default fail-closed publication gate.

Changes

• Adds �llow_stale_fhabs_rehearsal, default alse
• Adds habs_max_resource_age_days, default 14
• Sets CLEAR_LAKE_FHABS_MAX_RESOURCE_AGE_DAYS only when stale-source rehearsal is explicitly enabled
• Logs when stale FHABS rehearsal is deliberately allowed
• Renames artifacts to ormal-public-refresh-review-stale-source-rehearsal when that mode is used
• Updates the runbook and refresh design docs to mark stale-source rehearsal artifacts as review-only and non-publishable

Validation

• git diff --cached --check
• workflow and doc consistency reviewed locally

Boundary

This does not refresh or publish public data. It does not change advisory language, site assignments, or source interpretation. It creates a review-only rehearsal path for inspecting generated outputs when upstream FHABS resources lag the default freshness policy.

[coreytshaffer]

Merged as a scoped stale-source rehearsal policy layer.

This keeps the default formal refresh fail-closed while adding an explicit manual, review-only stale-source rehearsal mode. The override is opt-in, logged, reflected in artifact naming, and documented as non-publishable.

This does not refresh public data, weaken the publication gate, change advisory language, alter site assignments, or bundle unrelated dirty reviewer/GIS work.