[MFrancis-dev]

Implements the background worker (ARCHITECTURE §4.4).

What changed

• scheduleBuys (K5.3): per vault — skip when paused, not due, a buy is in flight, inside a 15-minute backoff after a skip/failure, or the vault is empty. Buys min(amount_per_run, balance). Real quote (fails closed on signature) → cost check → plan match → row inserted before execute_buy → deposit tx submitted (best effort). Skips, refusals and failures are recorded with a note; refusals and failures raise an alert.
• pollFunding (K5.2): 1Click status → credited / underpaid (alert) / refunded / failed; pending past the deadline → expired; one bad attempt never stops the rest.
• pollBuys (K5.4): final status with the actual amount out and destination tx; refunds noted with 1Click's reason (refunds return to the vault).
• expireQuotes + alerts (K5.5): DB-only expiry of unpaid quotes; keeper NEAR balance alert below 1 NEAR.
• Runner (K5.1): loops never overlap, errors are logged and the loop continues, SIGINT/SIGTERM wait for running ticks. JSON-line logs without secrets.
• buys.note column (migration 0001_buy_note).

Smoke run: pnpm worker with no env starts on PGlite, warns that the keeper isn't configured, and stops cleanly on SIGTERM.

Closes #50
Closes #51
Closes #52
Closes #53
Closes #54

Roadmap

• ROADMAP.md updated: K5.1–K5.5 done, Phase 5 at 100%

Checks

• 100 tests (16 worker tests covering every scheduler branch), pnpm typecheck, pnpm lint

NEAR HACKATHON rules

• No secrets; no funds moved; nothing signed with real keys