feat(codex): add semantic session affinity (#50)

* feat: add semantic Codex session affinity

* fix: satisfy Codex clippy tests

* fix: stabilize derived Codex sessions

* fix: align Codex synthetic session affinity

* fix: harden Codex session recovery chain

* fix: stabilize Codex bootstrap affinity

Author: acking-you

Cargo.lock

@@ -17,6 +17,7 @@ http = { workspace = true }
 reqwest = { workspace = true, features = ["stream", "multipart"] }
 serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
+sha2 = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true }
 tracing = { workspace = true }