Automate maintainer outreach review queue

[sajeetharan]

Summary

• add a durable, idempotent maintainer outreach review queue capped at 10 new candidates per day
• support explicit approve, reject, sent, and four-day follow-up workflows with at most two attempts
• add protected daily queue and weekly aggregate report schedules, operator scripts, setup tooling, tests, and the implementation PRD

Safety

• outreach delivery remains manual; application code does not send outreach messages
• only the aggregate weekly operator report is emailed
• queue records use lowercase login IDs and the /login Cosmos partition key

Validation

• npm test (395 passed, 0 failed)
• npm run build (72/72 static pages generated)
• git diff --check

PRD: docs/prd/maintainer-outreach-queue.md

Closes #384