GFQL native types T2: binder-time schema validation in strict mode (#1302)

[lmeyerov]

Summary

• add binder-time strict schema validation hooks against GraphSchemaCatalog for labels/properties
• emit deterministic strict diagnostics with alias/field/stage context + availability hints
• keep loose/default behavior unchanged unless strict mode is enabled
• add admitted/rejected + amplified strict/loose intersection tests

Validation

• python -m pytest -q graphistry/tests/compute/gfql/cypher/test_binder.py
• uv run ruff check graphistry/compute/gfql/frontends/cypher/binder.py graphistry/tests/compute/gfql/cypher/test_binder.py

Closes #1302