Preserve runtime workspace roots across thread resume (#43848)

## Why

Resuming a thread should retain its selected workspace folders, including additional roots and explicit empty selections. Resume overrides also need to survive a subsequent resume when no turn has run.

## What changed

- Persist `runtime_workspace_roots` in startup metadata and thread settings snapshots, separately from explicit environment selections and permission-profile roots.
- Restore roots from the latest snapshot owned by the resumed thread, falling back to owned startup metadata only when no snapshot exists. Honor explicit `runtimeWorkspaceRoots` overrides, retarget the old `cwd` root when `cwd` changes, deduplicate roots, and validate restored paths for the current host.
- Checkpoint effective settings on resume and restored settings after revert. Reload resume configuration if saved workspace roots change during loading.
- Normalize Windows rollout path spellings when matching thread search results, preserving selection of the correct rollout after revert, including compressed rollouts.

## Testing

Add regression coverage for workspace restoration, empty and explicit overrides, foreign paths, compaction and revert, resume checkpoints without recency changes, concurrent settings persistence, and rollout search path matching.

GitOrigin-RevId: d98d9d34dd63934d441120916c61c12b69e7f062

codex-rs/core/tests/suite/sqlite_state.rs

@@ -421,6 +421,7 @@ async fn backfill_scans_existing_rollouts() -> Result<()> {
                     parent_thread_id: None,
                     timestamp: "2026-01-27T12:00:00Z".to_string(),
                     cwd: codex_home.to_path_buf(),
+                    runtime_workspace_roots: None,
                     originator: "test".to_string(),
                     cli_version: "test".to_string(),
                     source: SessionSource::default(),