Wire the PatchUpdated events through app_server (#18289)

Wires patch_updated events through app_server. These events are parsed
and streamed while apply_patch is being written by the model. Also adds 500ms of buffering to the patch_updated events in the diff_consumer.

The eventual goal is to use this to display better progress indicators in
the codex app.

codex-rs/tui/src/chatwidget.rs

@@ -6540,6 +6540,7 @@ impl ChatWidget {
             | ServerNotification::ThreadUnarchived(_)
             | ServerNotification::RawResponseItemCompleted(_)
             | ServerNotification::CommandExecOutputDelta(_)
+            | ServerNotification::FileChangePatchUpdated(_)
             | ServerNotification::McpToolCallProgress(_)
             | ServerNotification::McpServerOauthLoginCompleted(_)
             | ServerNotification::AppListUpdated(_)