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/thread_lifecycle.rs

@@ -1,11 +1,7 @@
-use codex_protocol::ThreadId;
-
 use crate::ExtensionData;
 
 /// Input supplied when the host starts a runtime for a thread.
 pub struct ThreadStartInput<'a, C> {
-    /// Identifier for the thread whose runtime is starting.
-    pub thread_id: ThreadId,
     /// Host configuration visible at thread start.
     pub config: &'a C,
     /// Store scoped to the host session runtime.
@@ -16,8 +12,6 @@ pub struct ThreadStartInput<'a, C> {
 
 /// Input supplied when the host resumes an existing thread.
 pub struct ThreadResumeInput<'a> {
-    /// Identifier for the thread being resumed.
-    pub thread_id: ThreadId,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.
@@ -26,8 +20,6 @@ pub struct ThreadResumeInput<'a> {
 
 /// Input supplied when the host stops a thread runtime.
 pub struct ThreadStopInput<'a> {
-    /// Identifier for the thread whose runtime is stopping.
-    pub thread_id: ThreadId,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.

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

@@ -1,14 +1,9 @@
-use codex_protocol::ThreadId;
 use codex_protocol::protocol::TurnAbortReason;
 
 use crate::ExtensionData;
 
 /// Input supplied when the host starts a turn.
 pub struct TurnStartInput<'a> {
-    /// Identifier for the thread containing this turn.
-    pub thread_id: ThreadId,
-    /// Identifier for the turn that is starting.
-    pub turn_id: &'a str,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.
@@ -19,10 +14,6 @@ pub struct TurnStartInput<'a> {
 
 /// Input supplied when the host completes a turn.
 pub struct TurnStopInput<'a> {
-    /// Identifier for the thread containing this turn.
-    pub thread_id: ThreadId,
-    /// Identifier for the turn that is stopping.
-    pub turn_id: &'a str,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.
@@ -33,10 +24,6 @@ pub struct TurnStopInput<'a> {
 
 /// Input supplied when the host aborts a turn.
 pub struct TurnAbortInput<'a> {
-    /// Identifier for the thread containing this turn.
-    pub thread_id: ThreadId,
-    /// Identifier for the turn that is aborting.
-    pub turn_id: &'a str,
     /// Reason the host aborted the turn.
     pub reason: TurnAbortReason,
     /// Store scoped to the host session runtime.