Document why getcurrent snapshot lists gpt-5.4

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

test/snapshots/rpc_session_state/should_call_session_rpc_model_getcurrent.yaml

@@ -1,3 +1,11 @@
+# gpt-5.4 is listed here only because this is the first test in
+# rpc_session_state.e2e.test.ts to create a session. The runtime caches
+# /models per (auth, base_url) for 30 minutes (see capi_client.rs
+# LIST_MODELS_CACHE), so the first snapshot's models are reused by every
+# subsequent test sharing the same client. The "should call session rpc
+# model switchto" test needs gpt-5.4 in that cached list to validate.
+# If you reorder the tests, move this comment + entry to whichever test
+# now runs first.
 models:
   - claude-sonnet-4.5
   - gpt-5.4