Propagate temporary directories into sandbox policy contexts (#40660)

## Why

Filesystem policies containing `:tmpdir` need executor-local directory bindings,
including when execution occurs in a remote environment.

## What changed

- Cache temporary directories reported by remote executors and discover the
  equivalent directories for local environments.
- Preserve the cached directories across inherited environment selection and
  include them in `FileSystemSandboxContext`.
- Add `FileSystemSandboxPolicyContext` and a context accessor so filesystem
  policy entries can be resolved with the executor-owned current directory,
  workspace roots, and temporary directories.

## Testing

Extend environment-selection tests to cover local, remote, and inherited
temporary-directory policy context.

GitOrigin-RevId: 36335af3465c529f024bf69293af288803dd582d

codex-rs/protocol/src/permissions.rs

@@ -266,6 +266,17 @@ pub struct RawFileSystemSandboxPolicy {
     pub entries: Vec<RawFileSystemSandboxEntry>,
 }
 
+/// Executor-owned paths needed to interpret filesystem sandbox policy entries.
+///
+/// Orchestrator callers keep these as `PathUri` values until execution crosses
+/// into the executor that owns them.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct FileSystemSandboxPolicyContext<'a> {
+    pub cwd: &'a PathUri,
+    pub workspace_roots: &'a [PathUri],
+    pub temporary_directories: Option<&'a [PathUri]>,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 struct ResolvedFileSystemEntry {
     path: AbsolutePathBuf,