[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/thread-store/Cargo.toml

@@ -14,6 +14,16 @@ workspace = true
 [dependencies]
 async-trait = { workspace = true }
 chrono = { workspace = true, features = ["serde"] }
+codex-git-utils = { workspace = true }
 codex-protocol = { workspace = true }
+codex-rollout = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
+serde_json = { workspace = true }
 thiserror = { workspace = true }
+
+[dev-dependencies]
+codex-state = { workspace = true }
+pretty_assertions = { workspace = true }
+tempfile = { workspace = true }
+tokio = { workspace = true, features = ["macros"] }
+uuid = { workspace = true }