feat(security): DANGEROUS_SKIP explicit escape hatch + protocol & v17 migration support

[raymondginger2018-sudo]

Summary

Two related security improvements:

1. DANGEROUS_SKIP 显式命名危险逃生通道

Explicitly name the dangerous bypass channel as DANGEROUS_SKIP (borrowed from Claude Code), so the escape hatch is discoverable and auditable instead of implicit.

2. Protocol + v17 migration support for dangerous_skip access preset

Extend the protocol and v17 migration to support the dangerous_skip access preset, keeping the permission model consistent across versions.

[Zongwei9888]

Thanks for the PR. dangerous_skip maps to exactly the same permission mode, sandbox setting, filesystem scope and approval policy as full_access — the difference is only the name. For that, the change asks for a wire-protocol extension, a v17 schema migration (ALTER TABLE … DROP COLUMN, which also drops any dangerous_skip value on downgrade), regenerated TypeScript types, and — not included here — matching options in the Desktop and TUI pickers. That is a lot of surface for a label.

If we want the "name the danger explicitly" idea from Claude Code, the cheaper route is to make the existing full_access preset carry the warning in the UI copy and the audit log rather than add a fourth preset. This is the same half of #186 that we left out at the time, and the reasoning has not changed, so I am closing this one.