test: modernize Codex SQLite fixtures - #10

Summary

• update Rust and release-smoke SQLite fixtures with current Codex thread columns
• add millis timestamp indexes/triggers and cwd sort indexes from upstream migrations
• seed thread metadata fields like thread_source, preview, model, and reasoning effort
• add a regression test that asserts the fixture includes the current thread metadata columns

Tests

• cargo fmt --check
• cargo test --locked
• python3 -m py_compile scripts/smoke_release.py

Note: I did not run the full release smoke locally because it installs and uninstalls the fixed background-service label on this machine.