Add opt-in evidence-based workflow retrospectives

[eshulman2]

Summary

• add an opt-in, idempotent, non-blocking retrospective after terminal workflow outcomes
• build typed, bounded, redacted retrospective evidence
• generate evidence-linked deterministic recommendations for repeated failures, CI/review loops, and cost/latency signals
• publish retrospective reports to Jira
• keep deduplicated improvement-task creation separately disabled by default
• record analyzer usage and cost explicitly; the initial deterministic analyzer has zero model cost

Design

The retrospective cannot change the completed workflow outcome. The typed report provides an extension point for a future model-backed analyzer without requiring an additional LLM call in the initial implementation.

Test plan

• 74 focused retrospective and worker tests pass
• Ruff passes
• formatting checks pass
• successful, blocked, idempotent, redaction, and disabled-mode behavior covered

Closes #261

[eshulman2]

Closing to tighten terminal-outcome detection, restart/resume idempotency, and non-blocking lifecycle integration before reopening a Forge-native implementation.