feat: add Phase 3 durable effect execution

[eshulman2]

Summary

• add Redis and in-memory effect journals with atomic idempotent submission
• lease due effects and recover abandoned executions after lease expiry
• record structured success, precondition, retryable and terminal results
• execute provider operations through a narrow registry with bounded exponential retry
• index effect history by workflow run for inspection
• add an idempotent Jira comment executor with provider-side recovery evidence
• migrate resume acknowledgement comments from inline Jira calls to durable effects
• run the effect sweeper alongside the queue worker

Stack

• Depends on refactor: begin Phase 2 event interpretation boundary #325
• Implements Phase 3 slices 1–3
• Remaining direct provider writes and the operator/metrics surface stay as explicit follow-up slices documented in the Phase 3 plan

Correctness properties

• intent is persisted before provider execution
• duplicate submissions share one idempotency key and execute once
• retries execute the effect without rerunning its originating station
• expired execution leases are recoverable
• terminal records cannot be replayed from a stale due-set entry
• Jira comments are recovered by embedded effect identity after a crash between provider success and result persistence

Verification

• uv run ruff check src/
• uv run mypy src/forge/effects
• uv run pytest tests/unit/ -q --strict-markers — 2,412 passed
• uv run pytest tests/contracts tests/flows -q --strict-markers — 319 passed