[codex] Add local thread store listing (#17824)

Builds on top of #17659 

Move the filesystem + sqlite thread listing-related operations inside of
a local ThreadStore implementation and call ThreadStore from the places
that used to perform these filesystem/sqlite operations.

This is the first of a series of PRs that will implement the rest of the
local ThreadStore.

Testing:
- added unit tests for the thread store implementation
- adjusted some unit tests in the realtime + personality packages whose
callsites changed. Specifically I'm trying to hide ThreadMetadata inside
of the local implementation and make ThreadMetadata a sqlite
implementation detail concern rather than a public interface, preferring
the more generate StoredThread interface instead
- added a corner case test for the personality migration package that
wasn't covered by the existing test suite
- adjust the behavior of searched thread listing to run the existing
local rollout repair/backfill pass _before_ querying SQLite results, so
callers using ThreadStore::list_threads do not miss matches after a
partial metadata warm-up

codex-rs/core/src/state/service.rs

@@ -24,6 +24,7 @@ use codex_mcp::McpConnectionManager;
 use codex_models_manager::manager::ModelsManager;
 use codex_otel::SessionTelemetry;
 use codex_rollout::state_db::StateDbHandle;
+use codex_thread_store::LocalThreadStore;
 use std::path::PathBuf;
 use tokio::sync::Mutex;
 use tokio::sync::RwLock;
@@ -59,6 +60,7 @@ pub(crate) struct SessionServices {
     pub(crate) network_proxy: Option<StartedNetworkProxy>,
     pub(crate) network_approval: Arc<NetworkApprovalService>,
     pub(crate) state_db: Option<StateDbHandle>,
+    pub(crate) thread_store: LocalThreadStore,
     /// Session-scoped model client shared across turns.
     pub(crate) model_client: ModelClient,
     pub(crate) code_mode_service: CodeModeService,