feat(signals): classify issue-discovery lifecycle

[oktofeesh1]

Summary

• add deterministic issue-discovery lifecycle states
• include lifecycle state in issue-quality reports
• distinguish solved, valid solved, stale, duplicate, invalid, and closed-without-solver issues

What changed

• classifies lifecycle from issue state, labels, linked PRs, and recent merged PR context
• keeps direct-PR-first repos from encouraging issue filing through lifecycle warnings
• updates schema and focused tests for lifecycle state propagation
• keeps readiness integration fixtures current so freshness SLO assertions remain deterministic in CI

Why

• issue-quality guidance needs to separate valid solved issue-discovery activity from raw closed or stale issue activity.

Validation

• git diff --check
• npx tsc --noEmit
• npx vitest run test/unit/signals-v2.test.ts test/unit/local-branch.test.ts
• npm run test:coverage
• GitHub validate, Contributor trust, and Superagent Security Scan pass on the latest head

Closes #109

[chatgpt-codex-connector]

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[JSONbored]

@oktofeesh1 this is merge-ready from my pass.

• Deterministic: check rollup is green and merge-tree against current origin/main is clean.
• Maintainer judgment: lifecycle classification no longer treats broad bounty/reward wording as completion; it relies on issue state, labels, and cached linked solver PR evidence.
• Validation: tests cover stale, duplicate, invalid, closed-without-solver, solved, valid-solved, and unverified PR mentions.