Trust undecided local projects automatically (#36935)

## What changed

- Replace the TUI directory-trust prompt with automatic trust for local projects whose trust level is unset. Keep explicit trust settings and remote workspaces unchanged.
- Persist trust for the resolved Git or configured project root, then reload configuration so project-local settings take effect.
- Fall back to an in-memory trust override and an embedded app server when the config update cannot be persisted.

## Testing

- Cover persisted and in-memory trust, custom project-root markers, and the working directories selected by resume and fork flows.

GitOrigin-RevId: 8fd51eb4cd88267073324bfd7dc4106a56d7c745

codex-rs/tui/src/onboarding/mod.rs

@@ -1,7 +1,6 @@
 mod auth;
 mod keys;
 pub(crate) mod onboarding_screen;
-mod trust_directory;
 pub(crate) use auth::mark_underlined_hyperlink;
 pub(crate) use auth::mark_url_hyperlink;
 mod welcome;