Enrich thread archive analytics with thread context (#39797)

## What changed

- Add app-server client, runtime, thread source, and parent thread ID metadata to archive and unarchive analytics events when the reducer has that context.
- Omit non-automation feature thread sources and skip unavailable metadata.

## Testing

- Cover archive and unarchive event enrichment, filtered feature sources, and threads without cached context.
- Verify the app-server archive flow emits the enriched analytics payload.

GitOrigin-RevId: 163f9c30721cee0172bb4581b6dcd269e44cd941

codex-rs/analytics/src/client_tests.rs

@@ -448,6 +448,10 @@ async fn api_key_auth_sends_only_plugin_events_to_codex_backend() {
                     thread_id: "non-plugin-thread-archive".to_string(),
                     action: ThreadArchiveAction::Archived,
                     occurred_at_ms: 1,
+                    app_server_client: None,
+                    runtime: None,
+                    thread_source: None,
+                    parent_thread_id: None,
                 },
             }),
             sample_plugin_used_track_event("plugin-used", Some("sample@test")),