Move sqlite logs to a dedicated database (#13772)

## Summary
- move sqlite log reads and writes onto a dedicated `logs_1.sqlite`
database to reduce lock contention with the main state DB
- add a dedicated logs migrator and route `codex-state-logs` to the new
database path
- leave the old `logs` table in the existing state DB untouched for now

## Testing
- just fmt
- cargo test -p codex-state

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Co-authored-by: Codex <noreply@openai.com>

codex-rs/state/src/migrations.rs

@@ -1,3 +1,4 @@
 use sqlx::migrate::Migrator;
 
-pub(crate) static MIGRATOR: Migrator = sqlx::migrate!("./migrations");
+pub(crate) static STATE_MIGRATOR: Migrator = sqlx::migrate!("./migrations");
+pub(crate) static LOGS_MIGRATOR: Migrator = sqlx::migrate!("./logs_migrations");