docs(reentry): list runtime + execution modules in subpackage docstring

Wave-2 review nit: the subpackage docstring listed naming/scope/carry/rewrite
but not the existing `runtime` (compile-time rewrites) or the new `execution`
(data-frame stitching). Adds both for grep-navigability.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: lmeyerov

graphistry/compute/gfql/cypher/reentry/__init__.py

@@ -6,6 +6,8 @@
 - prefix carry-column / order helpers (``carry``)
 - AST/query rewriters that retarget reentry expressions onto carried columns
   (``rewrite``)
+- compile-time bounded-reentry query rewrites (``runtime``)
+- data-frame execution stitching for bounded reentry (``execution``; #987 Step 3)
 
 Public symbols are re-exported from ``cypher.lowering`` so existing imports
 (``from graphistry.compute.gfql.cypher.lowering import _reentry_hidden_column_name``)