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/core/src/state/turn.rs

@@ -1,6 +1,5 @@
 //! Turn-scoped state and active turn metadata scaffolding.
 
-use codex_extension_api::ExtensionData;
 use codex_sandboxing::policy_transforms::merge_permission_profiles;
 use indexmap::IndexMap;
 use std::collections::HashMap;
@@ -76,7 +75,6 @@ pub(crate) struct RunningTask {
     pub(crate) cancellation_token: CancellationToken,
     pub(crate) handle: AbortOnDropHandle<()>,
     pub(crate) turn_context: Arc<TurnContext>,
-    pub(crate) turn_extension_data: Arc<ExtensionData>,
     // Timer recorded when the task drops to capture the full turn duration.
     pub(crate) _timer: Option<codex_otel::Timer>,
 }
@@ -84,7 +82,6 @@ pub(crate) struct RunningTask {
 pub(crate) struct RemovedTask {
     pub(crate) records_turn_token_usage_on_span: bool,
     pub(crate) active_turn_is_empty: bool,
-    pub(crate) turn_extension_data: Arc<ExtensionData>,
 }
 
 impl ActiveTurn {
@@ -100,7 +97,6 @@ impl ActiveTurn {
         Some(RemovedTask {
             records_turn_token_usage_on_span,
             active_turn_is_empty: self.tasks.is_empty(),
-            turn_extension_data: task.turn_extension_data,
         })
     }
 
@@ -124,7 +120,6 @@ pub(crate) struct TurnState {
     pub(crate) tool_calls: u64,
     pub(crate) has_memory_citation: bool,
     pub(crate) token_usage_at_turn_start: TokenUsage,
-    pub(crate) extension_data: Arc<ExtensionData>,
 }
 
 pub(crate) struct PendingRequestPermissions {