Scope runtime workspace roots to execution environments (#32952)

## Why

Multi-environment turns can run against different filesystems, so a single
thread-wide workspace-root list cannot accurately describe every selected
environment.

## What changed

- Add optional `runtimeWorkspaceRoots` to each app-server environment selection.
  Omitted roots default to that environment's `cwd`, while an empty list selects
  no roots.
- Carry environment-native roots through turn selection, model-visible context,
  permission materialization, and tool sandboxing.
- Keep the top-level `runtimeWorkspaceRoots` field as a compatibility input when
  constructing default environment selections; explicit selections use their
  own roots.

## Testing

- Cover thread and turn API defaults, overrides, empty roots, and schema
  round-tripping.
- Verify foreign roots remain model-visible and remote execution applies the
  target environment's roots before sandbox selection.

GitOrigin-RevId: c6e7a62883c45c676c153055f46a55ee15a323a4

codex-rs/memories/write/src/runtime.rs

@@ -324,7 +324,7 @@ impl MemoryStartupContext {
     ) -> anyhow::Result<SpawnedConsolidationAgent> {
         let environments = self
             .thread_manager
-            .default_environment_selections(&config.cwd);
+            .default_environment_selections(&config.cwd, &config.workspace_roots);
         let NewThread {
             thread_id, thread, ..
         } = self