[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/personality_migration_tests.rs

@@ -7,6 +7,8 @@ use codex_protocol::protocol::SessionMeta;
 use codex_protocol::protocol::SessionMetaLine;
 use codex_protocol::protocol::SessionSource;
 use codex_protocol::protocol::UserMessageEvent;
+use codex_rollout::ARCHIVED_SESSIONS_SUBDIR;
+use codex_rollout::SESSIONS_SUBDIR;
 use pretty_assertions::assert_eq;
 use tempfile::TempDir;
 use tokio::io::AsyncWriteExt;
@@ -25,6 +27,16 @@ async fn write_session_with_user_event(codex_home: &Path) -> io::Result<()> {
         .join("2025")
         .join("01")
         .join("01");
+    write_rollout_with_user_event(&dir, thread_id).await
+}
+
+async fn write_archived_session_with_user_event(codex_home: &Path) -> io::Result<()> {
+    let thread_id = ThreadId::new();
+    let dir = codex_home.join(ARCHIVED_SESSIONS_SUBDIR);
+    write_rollout_with_user_event(&dir, thread_id).await
+}
+
+async fn write_rollout_with_user_event(dir: &Path, thread_id: ThreadId) -> io::Result<()> {
     tokio::fs::create_dir_all(&dir).await?;
     let file_path = dir.join(format!("rollout-{TEST_TIMESTAMP}-{thread_id}.jsonl"));
     let mut file = tokio::fs::File::create(&file_path).await?;
@@ -85,6 +97,22 @@ async fn applies_when_sessions_exist_and_no_personality() -> io::Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn applies_when_only_archived_sessions_exist_and_no_personality() -> io::Result<()> {
+    let temp = TempDir::new()?;
+    write_archived_session_with_user_event(temp.path()).await?;
+
+    let config_toml = ConfigToml::default();
+    let status = maybe_migrate_personality(temp.path(), &config_toml).await?;
+
+    assert_eq!(status, PersonalityMigrationStatus::Applied);
+    assert!(temp.path().join(PERSONALITY_MIGRATION_FILENAME).exists());
+
+    let persisted = read_config_toml(temp.path()).await?;
+    assert_eq!(persisted.personality, Some(Personality::Pragmatic));
+    Ok(())
+}
+
 #[tokio::test]
 async fn skips_when_marker_exists() -> io::Result<()> {
     let temp = TempDir::new()?;