T12: Create LLMRedactionJob for async processing

[dpaluy]

Task Details

Priority: p2 | Story Points: 3 | Group: C (Integration)
Depends on: T11

Files

• app/jobs/tracebook/llm_redaction_job.rb
• test/jobs/llm_redaction_job_test.rb

Acceptance Criteria

• Retry policy: 3 attempts with exponential backoff
• Updates audit on success/failure
• Skips already-processed interactions
• Pessimistic lock prevents race conditions

Context

Part of PII Redaction Architecture Refactor - Phase 3: LLM Redactor

See full plan: docs/plans/260106-02b-pii-redaction-architecture.md