Gate paginated thread history on the state database (#35787)

## Why

Local thread stores without an initialized state database should not implicitly
create SQLite files or partially delete threads that have materialized history.

## What changed

- Report paginated history listing as unsupported when no state database is
  available, and skip history projection and materialization in that mode.
- Reject paginated forks without a state database.
- Validate access to materialized history before deleting rollout files, so a
  failed deletion preserves both the rollout and its history rows.

## Testing

Added coverage that a store without a state database creates no SQLite files
and preserves materialized history when deletion is unsupported. Existing
projection tests now initialize the state runtime explicitly.

GitOrigin-RevId: 2eaa0f5f0de8d5e4d84375ec50b310746a0ee68e

codex-rs/thread-store/src/local/thread_history_materialization.rs

@@ -26,6 +26,9 @@ pub(super) async fn materialize_to_sqlite(
     thread_id: ThreadId,
     rollout_path: &Path,
 ) -> ThreadStoreResult<()> {
+    if store.state_db.is_none() {
+        return Ok(());
+    }
     let start_offset = super::thread_history::projection_state(store, thread_id)
         .await?
         .map_or(0, |state| state.next_byte_offset);