app-server: Replay pending item requests on thread/resume (#12560)

Replay pending client requests after `thread/resume` and emit resolved
notifications when those requests clear so approval/input UI state stays
in sync after reconnects and across subscribed clients.

Affected RPCs:
- `item/commandExecution/requestApproval`
- `item/fileChange/requestApproval`
- `item/tool/requestUserInput`

Motivation:
- Resumed clients need to see pending approval/input requests that were
already outstanding before the reconnect.
- Clients also need an explicit signal when a pending request resolves
or is cleared so stale UI can be removed on turn start, completion, or
interruption.

Implementation notes:
- Use pending client requests from `OutgoingMessageSender` in order to
replay them after `thread/resume` attaches the connection, using
original request ids.
- Emit `serverRequest/resolved` when pending requests are answered
or cleared by lifecycle cleanup.
- Update the app-server protocol schema, generated TypeScript bindings,
and README docs for the replay/resolution flow.

High-level test plan:
- Added automated coverage for replaying pending command execution and
file change approval requests on `thread/resume`.
- Added automated coverage for resolved notifications in command
approval, file change approval, request_user_input, turn start, and turn
interrupt flows.
- Verified schema/docs updates in the relevant protocol and app-server
tests.

Manual testing:
- Tested reconnect/resume with multiple connections.
- Confirmed state stayed in sync between connections.

codex-rs/app-server/src/thread_state.rs

@@ -1,5 +1,6 @@
 use crate::outgoing_message::ConnectionId;
 use crate::outgoing_message::ConnectionRequestId;
+use codex_app_server_protocol::RequestId;
 use codex_app_server_protocol::ThreadHistoryBuilder;
 use codex_app_server_protocol::Turn;
 use codex_app_server_protocol::TurnError;
@@ -28,8 +29,16 @@ pub(crate) struct PendingThreadResumeRequest {
     pub(crate) config_snapshot: ThreadConfigSnapshot,
 }
 
+// ThreadListenerCommand is used to perform operations in the context of the thread listener, for serialization purposes.
 pub(crate) enum ThreadListenerCommand {
-    SendThreadResumeResponse(PendingThreadResumeRequest),
+    // SendThreadResumeResponse is used to resume an already running thread by sending the thread's history to the client and atomically subscribing for new updates.
+    SendThreadResumeResponse(Box<PendingThreadResumeRequest>),
+    // ResolveServerRequest is used to notify the client that the request has been resolved.
+    // It is executed in the thread listener's context to ensure that the resolved notification is ordered with regard to the request itself.
+    ResolveServerRequest {
+        request_id: RequestId,
+        completion_tx: oneshot::Sender<()>,
+    },
 }
 
 /// Per-conversation accumulation of the latest states e.g. error message while a turn runs.