Per-message override: reprocess or exclude from menu

[CosmicCEO]

Sprint: sprint-4 (files: Unload_AttachmentsApp.swift, MailBridge.swift)

Add a way to select a recent processed message from the menu and force reprocess it or mark it permanently excluded. MailBridge exposes a manual-trigger entry point; Unload_AttachmentsApp adds the menu affordance.

Acceptance criteria

• A message flagged "exclude" is never touched on future runs even if it still matches extraction rules.
• "Reprocess" re-runs the full pipeline on a specific UID on demand.