chore(miner-discovery): re-scope and reopen #1060 for metadata-only cross-repo fan-out

[JSONbored]

#1060 ("proactive cross-repo opportunity discovery") was closed under the assumption that discovery spans only registered repos and a global data layer. Phase 1 of the miner roadmap replaces that with a metadata-only, fully client-driven GitHub search/listing fan-out across any repos the contributor points the miner at — no dependency on any Gittensory-registered repo set, no dependency on any retired/central global data layer, and no source clone. This issue is the paper trail: it documents the re-scope so #1060 can be reopened with an accurate deliverable list, and it seeds the tracking issue every other Phase 1 issue below references.

No code change here — this is a scope-correction note plus the reopen action, so the miner backlog has one canonical entry point instead of a stale closed issue that undersells what's being built.

Deliverables

• Reopen JSONbored/gittensory#1060 and update its body: discovery is metadata-only (GitHub search/listing APIs only, never source clone), fan-out is client-driven (the contributor supplies the repo list / search scope — no dependency on a Gittensory-registered-repos table), and there is no dependency on any retired global data layer.
• Add a short "Phase 1 scope" section to feat(miner): proactive cross-repo opportunity discovery — "best issue to build right now" #1060 cross-linking every issue in this batch (the ranker, the goal model, the AI-policy map, the new gittensory_find_opportunities tool, and this note) so a reader lands on one coherent plan.
• Note in feat(miner): proactive cross-repo opportunity discovery — "best issue to build right now" #1060 that src/services/issue-quality.ts (52 lines) and src/signals/reward-risk.ts opportunity factors (competitionFactor / freshnessFactor, ~line 88-93) are the two existing per-repo signal sources the new cross-repo ranker composes — it is a new join over existing signals, not a new model.
• Confirm and record in feat(miner): proactive cross-repo opportunity discovery — "best issue to build right now" #1060 that all deliverables in this Phase 1 batch are read-only / no-GitHub-writes (wave: "1"), matching the safety split for this phase.

References

• JSONbored/gittensory#1060 (closed issue being re-scoped)
• JSONbored/gittensory#1058 (parent epic: "close the loop")
• src/services/issue-quality.ts (52 lines) — existing per-repo issue ranking
• src/signals/reward-risk.ts (877 lines) — existing opportunity factors (competitionFactor, freshnessFactor)
• src/services/decision-pack.ts (1845 lines) — existing per-repo opportunity pack

[linear-code]

JSO-2396