feat(miner-manage): append-only local event ledger for the manage/loop phase

[JSONbored]

The miner needs an immutable, append-only event log (distinct from the mutable portfolio table in the schema foundation issue) so every state transition a PR goes through — opened, polled, ci_passed, ci_failed, gate_merged, gate_closed, rejected, disengaged — is replayable and auditable locally, mirroring the spirit of the cloud review_audit ledger but 100% client-side.

Deliverables

• packages/gittensory-miner/src/state/event-ledger.ts — appendEvent() (insert-only, never update/delete) and readEvents(filter)
• Event type union covering the manage/loop lifecycle (opened, ci_status_changed, gate_verdict_observed, outcome_recorded, rejection_handled, loop_reentered)
• Each event row is self-contained JSON with a monotonic sequence number per run
• Unit tests: append-only invariant (no update path exists), ordering, and filter-by-run/by-type

References

• packages/gittensory-miner/src/state/schema.ts (new, from the schema-foundation issue — this ledger is a sibling table in the same local DB)
• migrations/0049_review_audit_parity.sql — cloud audit-ledger naming precedent (event_type discriminator column) to mirror in spirit only
• New: packages/gittensory-miner/src/state/event-ledger.ts

[linear-code]

JSO-2419