S4: reduce CompiledCypher compatibility surface (#1305)

[lmeyerov]

Summary

• reduce CompiledCypher compatibility accessor surface by retiring unused derived properties
• rewire active compile/runtime call sites to read canonical nested execution_extras payloads
• update lowering tests to assert canonical surfaces and add changelog entry

Surface reductions

• CompiledCypherQuery: removed properties connected_optional_match, connected_match_join, query_graph, scope_stack, logical_plan_route
• CompiledGraphBinding: removed logical_plan_route
• CompiledCypherGraphQuery: removed logical_plan_route

Validation

• ./bin/ruff.sh graphistry/compute/gfql/cypher/lowering.py graphistry/compute/gfql/cypher/reentry/runtime.py graphistry/compute/gfql_unified.py graphistry/tests/compute/gfql/cypher/test_lowering.py
• ./bin/pytest.sh graphistry/tests/compute/gfql/cypher/test_lowering.py -q
• ./bin/pytest.sh graphistry/tests/compute/test_gfql.py -q

Refs #1305
Parent #1260