GFQL/Cypher: harden #989 row-carrier plan metadata

[lmeyerov]

Summary

• harden Cypher/GFQL: introduce a first-class row-carrier IR for multi-stage vectorized row semantics #989 row-carrier plan metadata by making non-source alias property dependencies explicit on ReentryPlan.aliases[*].carried_properties
• preserve master's reentry module split by implementing the metadata wiring in graphistry/compute/gfql/cypher/reentry/compiletime.py while keeping reentry/runtime.py as a compatibility wrapper
• add compile-contract regressions for carried-property metadata in both carried-alias and free-form reentry lanes
• add changelog entry under [Development] Internal

Key Changes

• graphistry/compute/gfql/cypher/lowering.py
  • _demote_secondary_whole_row_aliases() now returns secondary alias property metadata map
• graphistry/compute/gfql/cypher/reentry/compiletime.py
  • merge demoted/scanned/bridge-carried properties into one map before ReentryPlan construction
  • populate CarriedAlias(..., carried_properties=...) for non-source aliases
  • use merged map for downstream hidden-property rewrite metadata
• graphistry/compute/gfql/cypher/reentry_plan.py
  • doc contract updated to reflect explicit carried property tracking
• graphistry/tests/compute/gfql/cypher/test_lowering.py
  • add compile-contract tests for non-source carried property metadata (standard + free-form)
• CHANGELOG.md
  • development internal entry for Cypher/GFQL: introduce a first-class row-carrier IR for multi-stage vectorized row semantics #989 metadata hardening

Validation

• python -m pytest graphistry/tests/compute/gfql/cypher/test_lowering.py -k "reentry and not cudf"
• uv run ruff check graphistry/compute/gfql/cypher/lowering.py graphistry/compute/gfql/cypher/reentry/compiletime.py graphistry/compute/gfql/cypher/reentry/runtime.py graphistry/compute/gfql/cypher/reentry_plan.py graphistry/tests/compute/gfql/cypher/test_lowering.py
• python bin/ci_cypher_surface_guard.py

Closes #989