Three fixes in run_tests.ml defhandler parser:
1. Extract &key param names, store in hdef["params"]. run-handler
binds them from mock args before evaluating — fixes row-editing,
tabs, inline-edit, profile-editing handlers.
2. Capture all body forms after params, wrap in (do ...) when
multiple — fixes ex-slow (sleep before let).
3. Register all HTML tags as native fns via Sx_render.html_tags —
fixes ex-bulk (tr tag), and enables aser to serialize any tag.
1352 → 1361 passing tests.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>