feat(maintainers): build PR review queue intelligence

[JSONbored]

Parent: #32

Goal

Help maintainers decide what to review now, defer, redirect, or ignore.

Requirements

• Build repo-level PR queue intelligence from confirmed-miner status, author role, linked issue quality, tests/checks, duplicate risk, stale status, PR size, and queue burden.
• Produce private maintainer recommendations: review_now, needs_author, watch, redirect, maintainer_lane.
• Keep public GitHub comments sanitized and quiet-by-default.
• Feed queue intelligence into repo intelligence and maintainer packets.

Acceptance Criteria

• Maintainer packet can rank PRs by reviewability and burden reduction.
• Non-miner PRs do not produce public surfaces.
• Confirmed-miner public output remains minimal and safe.
• No private reviewability score leaks publicly.

Testing Requirements

This issue must preserve the repo's CI gate:

• npm run test:ci must pass.
• Global coverage must remain at or above 95% for lines, statements, functions, and branches.
• Add or update tests for every new branch, fallback path, sanitizer rule, and regression.
• Add invariant/property-style tests when behavior depends on sorting, gating, public/private boundaries, scoring, queue pressure, or source-upload safety.
• Public GitHub output must be tested against forbidden language: wallet, hotkey, raw trust score, payout, reward estimate, farming, private reviewability, and public score estimate.

Required Test Scenarios

• Review-now PR.
• Needs-author PR.
• Duplicate-prone PR.
• Maintainer-lane PR.
• Non-miner quiet skip.
• Public/private sanitizer regression.
• Large queue performance fixture.