feat: recover data history and archive vintages

[jonit-dev]

Status

PARTIAL: the full data-history/vintage implementation and offline tests are present. Real ALFRED history, committed vintage archives, live OI growth, and live on-chain missingness proof are blocked because no FRED_API_KEY exists locally or in GitHub repository secrets.

Source PRD: docs/PRDs/2026-08-02/DATA_HISTORY_RECOVERY_AND_VINTAGE_ARCHIVE.md (authoritative local input for this swarm run).

Changes

• Added deterministic merge-by-key retention/precedence, named environment errors, append-only NDJSON vintages, and vintage reconstruction.
• Updated all seven data updaters to merge caches and append vintages; added ALFRED/FRED macro URL construction and source freshness caps.
• Added bounded three-day on-chain forward-fill reasons and insufficient-data regime handling.
• Wired FRED_API_KEY into the data-only forecast refresh workflow and added coverage/freshness tests.

Verification

• yarn test: PASS, 27 files / 116 tests.
• yarn lint: PASS.
• yarn build: PASS; existing large-chunk warning only.
• yarn build:features: PASS, 5,842 rows.
• yarn backtest: PASS quality and robustness gates.
• yarn validate:features: expected FAIL, futuresOpenInterestUSD 28/30.
• yarn check:freshness: expected FAIL on stale baseline sources versus declared caps.
• yarn validate:data: known baseline FAIL, 5,722 CoinMetrics MVRV mismatches.

No fabricated src/data/vintages records were committed. The workflow has no deployment step.

External blocker / merge condition

FRED_API_KEY is absent and gh secret list is empty. The exact unblock is:

export FRED_API_KEY='<real-key>'
yarn update:macro

Do not claim the real 2010+ macro/vintage acceptance or merge this PR as complete until the real updater run produces and verifies the archives, reconstruction, and growing OI history.