feat(agent): monitor existing PRs and generate next-step packets

[JSONbored]

Parent: #32

Goal

Help miners improve or clean up already-open PRs before opening more work.

Requirements

• Add MCP/API flow to inspect a contributor’s open PRs across registered repos.
• Classify each PR as approved, blocked, stale, needs author, failing checks, missing tests, duplicate-prone, reviewable, or should close/withdraw.
• Generate next-step packets from metadata only.
• Feed open PR pressure into scoreability and cleanup-first guidance.

Acceptance Criteria

• MCP can answer “what should I do with my open PRs right now?”
• Approved/mergeable PRs appear in pending scenario projections.
• Failing checks and review comments become actionable next steps.
• Maintainer-authored PRs are treated as maintainer-lane context.

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

• Approved PR.
• Failing checks.
• Review changes requested.
• Stale PR.
• Duplicate-prone PR.
• Maintainer-authored PR.
• Source-upload guard.