Email Humanizer: opt-in AI rewrite with OpenAI support, config hierarchy, and settings UI

Features

• Email Humanizer: opt-in AI rewrite with OpenAI support, config hierarchy, and settings UI
• Human-in-the-Loop approval flow for outbound emails
• Safety engine: prompt injection defenses, thread integrity checks, and active mitigation (block, quarantine, hold)
• Smarter email classification with weighted scoring and adversarial detection
• Inbound emails now count toward your usage quota
• Security hardening across agent endpoints and webhooks
• E2E dogfood rollout with alerting for agent mailboxes
• Human override workspace with queue views and operator actions

Fixes

• Fixed rate limiter dependency injection causing startup failures
• Fixed background job connections not closing on shutdown
• Fixed CORS issues with authentication
• Fixed inbound email endpoint errors