Add executor-context filesystem permission helpers (#43939)

## Why

Filesystem policies for remote execution need to interpret paths, home directories, and temporary directories using the execution host's context.

## What changed

- Add context-based read-denial matching, read-access checks, glob resolution, and `PathUri` workspace-write constructors without consulting local paths or environment variables.
- Share managed read-denial validation through `DenyReadValidator` and use it in core configuration, preserving required-entry checks, concrete grant validation, and constraint diagnostics.
- Reject invalid or unresolvable denial paths when constructing a context-based matcher, and apply `/tmp` denials according to the execution host's path convention.
- Preserve workspace-root symbols and protected metadata entries when materializing URI-based writable roots.

## Testing

Add regression tests for POSIX, Windows, and UNC path matching; conflicting read and write grants; malformed or unresolvable denials; `/tmp` handling; and workspace metadata protection.

GitOrigin-RevId: aa2b174288d1172ab52ff485f58d306236d27652

codex-rs/protocol/src/models.rs

@@ -550,6 +550,24 @@ impl PermissionProfile {
         }
     }
 
+    /// Legacy workspace-write settings interpreted for executor-owned paths.
+    pub fn workspace_write_with_path_uris(
+        writable_roots: &[PathUri],
+        network: NetworkSandboxPolicy,
+        exclude_tmpdir_env_var: bool,
+        exclude_slash_tmp: bool,
+    ) -> Self {
+        let file_system = FileSystemSandboxPolicy::workspace_write_with_path_uris(
+            writable_roots,
+            exclude_tmpdir_env_var,
+            exclude_slash_tmp,
+        );
+        Self::Managed {
+            file_system: ManagedFileSystemPermissions::from_sandbox_policy(&file_system),
+            network,
+        }
+    }
+
     pub fn materialize_project_roots_with_workspace_roots(
         self,
         workspace_roots: &[AbsolutePathBuf],