Record externally completed agent config imports (#34981)

## Why

Clients that complete an external agent config import outside the app server need a way to include the result in import history.

## What changed

- Add `externalAgentConfig/import/recordHistory` to persist completed item results and return a generated import ID.
- Store the optional provider ID for regular imports and expose it when reading import history.
- Update the generated JSON and TypeScript protocol schemas for the new request, response, and history field.

## Testing

- Cover recording and reading an externally completed import through the app-server protocol.
- Cover provider ID persistence and updates in the state runtime.

GitOrigin-RevId: 935401e899ec9eeb38f54c182e45a16642411deb

codex-rs/app-server-protocol/src/protocol/common.rs

@@ -1155,6 +1155,11 @@ client_request_definitions! {
         serialization: global("config"),
         response: v2::ExternalAgentConfigImportResponse,
     },
+    ExternalAgentConfigImportHistoryRecord => "externalAgentConfig/import/recordHistory" {
+        params: v2::ExternalAgentConfigImportHistoryRecordParams,
+        serialization: global("config"),
+        response: v2::ExternalAgentConfigImportHistoryRecordResponse,
+    },
     ExternalAgentConfigImportHistoriesRead => "externalAgentConfig/import/readHistories" {
         params: #[ts(type = "undefined")] #[serde(skip_serializing_if = "Option::is_none")] Option<()>,
         serialization: global_shared_read("config"),