feat: move extension scope ids into ExtensionData (#22490)

## Summary
- add a scoped level_id to ExtensionData and expose it through
level_id()
- remove thread_id/turn_id parameters from extension contributor inputs
where the scoped ExtensionData already carries that identity
- move turn-scoped extension data onto TurnContext so token usage and
lifecycle contributors can share the same turn store

## Testing
- cargo check -p codex-extension-api -p codex-core --tests
- cargo test -p codex-extension-api
- cargo test -p codex-guardian
- cargo test -p codex-core --lib
record_token_usage_info_notifies_extension_contributors
- cargo test -p codex-core --lib
submission_loop_channel_close_emits_thread_stop_lifecycle
- cargo test -p codex-core --lib
submission_loop_channel_close_aborts_active_turn_before_thread_stop_lifecycle
- just fix -p codex-extension-api
- just fix -p codex-guardian
- just fix -p codex-core
- just fmt

## Note
- Attempted cargo test -p codex-core; it aborted in
agent::control::tests::spawn_agent_fork_last_n_turns_keeps_only_recent_turns
with the existing stack overflow before the full suite completed.

codex-rs/ext/extension-api/src/contributors.rs

@@ -1,7 +1,6 @@
 use std::future::Future;
 use std::sync::Arc;
 
-use codex_protocol::ThreadId;
 use codex_protocol::items::TurnItem;
 use codex_protocol::protocol::ReviewDecision;
 use codex_protocol::protocol::TokenUsageInfo;
@@ -79,8 +78,7 @@ pub trait TokenUsageContributor: Send + Sync {
         &self,
         _session_store: &ExtensionData,
         _thread_store: &ExtensionData,
-        _thread_id: ThreadId,
-        _turn_id: &str,
+        _turn_store: &ExtensionData,
         _token_usage: &TokenUsageInfo,
     ) {
     }