Integrate native agents and polish access workflows

[singchia]

Summary

• Discover and use existing Codex installations through owner-scoped Edge sessions.
• Persist encrypted conversation history, paginate completed rounds, and keep display limits independent from execution lifetime.
• Display execution details, native questions, approvals, model selection and session controls.
• Improve application probing, access creation, saved-password status, empty states and token charts.
• Fix host heartbeat reporting and installation completion feedback.

Validation

• Full Go tests and go vet passed.
• Agent, control-plane and DAO race tests passed.
• Web build and Chinese/English, light/dark, desktop/mobile browser regressions passed.
• Real Codex question/answer/continuation in an isolated plan-mode test passed.
• Test deployment verified with two real turns, encrypted history pages and native resume.

Boundaries

• History does not expire. Extremely long individual rounds may truncate display content without stopping execution.
• Windows discovery is supported; native Windows launch remains disabled pending supervision support.
• Additive database schema. Rollback must retain history tables and the encryption secret.