feat(retained): admit portable context transfers

[drewstone]

Summary

• Admit portable context for one exact fresh destination.
• Recover accepted transfers after a server restart.
• Keep conversation text out of the durable operation ledger.
• Separate retained readiness from the public health timeout.
• Update all direct dependencies to current releases.

Proof

• pnpm test: 1,028 passed and 11 skipped.
• pnpm typecheck: passed.
• pnpm outdated --format json: no outdated direct dependencies.
• The route test proves transferred messages reach the backend request.
• The restart test proves SQLite contains no portable message text.