## Why
`--worktree` previously supported only `codex exec` and `codex exec fork`. Interactive sessions need the same managed checkout support, with configuration and policy resolved for the destination before starting a turn.
## What changed
- Enable `codex --worktree` and `codex fork --worktree <session-id>` behind the `worktrees` feature, restricted to local sessions. Interactive forks require an explicit session selector.
- Resolve interactive and exec worktree forks from the session's latest saved working directory unless `--cd` is supplied. Keep relative `--add-dir` paths anchored to the invocation directory.
- Load interactive destination configuration before telemetry and login policy initialization, and bind checkout ownership before the first turn.
- Reject explicitly untrusted sources, including when destination cloud policy or refreshed configuration reveals distrust. Retain unbound interactive checkouts after startup failure and report manual recovery instructions.
## Testing
Add CLI integration and TUI tests for startup and named forks, destination instructions and configuration, ownership before the first request, trust enforcement, and retained-checkout recovery. Extend exec coverage for saved fork directories, explicit `--cd`, relative writable roots, and cloud policy rejection.
GitOrigin-RevId: 371583f7feca73b218a4ff188b2b85812c8439e6
