Daemon job, search, and transfer history

[fiso64]

• Add SQLite-backed durable history for jobs, workflows, searches, results, transfers, and attempts.
• Serve retained history after restarts and reconcile interrupted daemon sessions.
• Add retention controls, health and maintenance APIs, platform data-directory defaults, and sockseek database maintenance commands.

Overly detailed LLM-written plan file: https://github.com/fiso64/sockseek/blob/7e5a071f1ed7038661fbced6892e197ee3f69933/docs/temp/PERSISTENCE-DISCUSSION.md

[fiso64]

Persistence has been merged into the v4 integration branch.