[config] Detect git worktrees for project trust (#2585)

## Summary
When resolving our current directory as a project, we want to be a
little bit more clever:
1. If we're in a sub-directory of a git repo, resolve our project
against the root of the git repo
2. If we're in a git worktree, resolve the project against the root of
the git repo

## Testing
- [x] Added unit tests
- [x] Confirmed locally with a git worktree (the one i was using for
this feature)

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

@@ -1,6 +1,7 @@
 use std::path::PathBuf;
 
 use codex_core::config::set_project_trusted;
+use codex_core::git_info::resolve_root_git_project_for_trust;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
 use ratatui::buffer::Buffer;
@@ -144,10 +145,11 @@ impl StepStateProvider for TrustDirectoryWidget {
 
 impl TrustDirectoryWidget {
     fn handle_trust(&mut self) {
-        if let Err(e) = set_project_trusted(&self.codex_home, &self.cwd) {
+        let target =
+            resolve_root_git_project_for_trust(&self.cwd).unwrap_or_else(|| self.cwd.clone());
+        if let Err(e) = set_project_trusted(&self.codex_home, &target) {
             tracing::error!("Failed to set project trusted: {e:?}");
-            self.error = Some(e.to_string());
-            // self.error = Some("Failed to set project trusted".to_string());
+            self.error = Some(format!("Failed to set trust for {}: {e}", target.display()));
         }
 
         self.selection = Some(TrustDirectorySelection::Trust);