feat(signals): model issue-discovery lifecycle state separately

[JSONbored]

Parent roadmap: #82

Background

Issue-discovery outcomes affect credibility and contributor strategy differently from direct PR outcomes.

Goal

Build a separate issue-discovery lifecycle model for open, closed-not-solved, solved, valid-solved, stale, duplicate, and invalid states.

Current Behavior

Issue and PR signals exist, but issue-discovery lifecycle is not fully separated from generic issue quality.

Desired Behavior

Decision packs and issue-quality reports explain which issue-discovery activity helps, hurts, or should be avoided.

Implementation Requirements

• Add lifecycle classifier.
• Use official/mirror data first.
• Separate valid solved issues from raw closed issues.
• Feed lifecycle into issue quality, strategy, and scoring profile.
• Avoid encouraging issue filing in direct-PR-only repos.

Public/Private Output Boundaries

Signal data can inform private API/MCP outputs. Public GitHub output must use only sanitized, maintainer-friendly summaries and must not expose private scoreability or contributor scoring internals.

Acceptance Criteria

• Valid solved issues are distinct from raw solved/closed.
• Closed-not-solved affects risk.
• Direct-PR-only repos do not encourage issue spam.
• Lifecycle state is deterministic.

Testing Requirements

• npm run test:ci must pass.
• Global coverage must remain at or above 97% for lines, statements, functions, and branches.
• Aim for 98%+ branch coverage locally to avoid CI variance.
• Add tests for every new branch, fallback path, sanitizer rule, and regression.
• Add invariant/property-style tests when behavior depends on sorting, gating, scoring, queue pressure, source-upload safety, public/private boundaries, or upstream drift.
• Public GitHub output must be tested against forbidden language: wallet, hotkey, raw trust score, payout, reward estimate, farming, private reviewability, and public score estimate.
• MCP/local tooling must prove source contents are not uploaded.

Additional Test Scenarios

• Valid solved fixture.
• Closed-not-solved fixture.
• Stale issue fixture.
• Direct-PR-only fixture.
• Issue-discovery repo fixture.