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/mod.rs

@@ -207,6 +207,11 @@ impl LocalThreadStore {
     }
 
     async fn thread_history_db(&self) -> ThreadStoreResult<&sqlx::SqlitePool> {
+        if self.state_db.is_none() {
+            return Err(ThreadStoreError::Unsupported {
+                operation: "paginated_history",
+            });
+        }
         self.thread_history_db
             .get_or_try_init(|| async {
                 codex_state::open_thread_history_db(&self.config.sqlite).await
@@ -452,7 +457,7 @@ impl ThreadStore for LocalThreadStore {
     }
 
     fn supports_paginated_history_lists(&self) -> bool {
-        true
+        self.state_db.is_some()
     }
 
     fn list_turns(&self, params: ListTurnsParams) -> ThreadStoreFuture<'_, TurnPage> {