docs(changelog): restore missing cuDF same-path and test entries

Author: lmeyerov

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - **GFQL / reference**: Extended the pandas reference enumerator and parity tests to cover hop ranges, labeling, and slicing so GFQL correctness checks include the new traversal shapes.
 - **Docs / GFQL**: Documented the external `tck-gfql` conformance harness and local run instructions in GFQL docs.
 - **GFQL / WHERE** (experimental): Added `Chain.where` field for same-path WHERE clause constraints. New modules: `same_path_types.py`, `same_path_plan.py`, `df_executor.py` implementing Yannakakis-style semijoin reduction for efficient WHERE filtering. Supports equality, inequality, and comparison operators on named alias columns.
+- **GFQL / cuDF same-path**: Added execution-mode gate `GRAPHISTRY_CUDF_SAME_PATH_MODE` (auto/oracle/strict) for GFQL cuDF same-path executor. Auto falls back to oracle when GPU unavailable; strict requires cuDF or raises.
 
 ### Performance
 - **GFQL / chain**: Optimized backward pass for simple single-hop edges by skipping full `hop()` call and using vectorized merge filtering instead (~50% faster on small graphs). Added `is_simple_single_hop()` method on `ASTEdge` for optimization eligibility checks.
@@ -32,6 +33,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - **GFQL / hop**: Expanded `test_compute_hops.py` and GFQL parity suites to assert branch pruning, bounded outputs, label collision handling, and forward/reverse slice behavior.
 - **Reference enumerator**: Added oracle parity tests for hop ranges and output slices to guard GFQL integrations.
 - **GFQL / chain**: Added 78 tests for backward pass and combine_steps optimizations covering edge cases, direction semantics, hop labels, and multi-step chains.
+- **GFQL / df_executor**: Added comprehensive test suite (core, amplify, patterns, dimension) with 200+ tests covering Yannakakis semijoin, WHERE clause filtering, multi-hop paths, and pandas/cuDF parity.
+- **GFQL / cuDF same-path**: Added strict/auto mode coverage for cuDF executor fallback behavior.
 
 ### Infra
 - **Tooling**: `bin/flake8.sh` / `bin/mypy.sh` now require installed tools (no auto-install), honor `FLAKE8_CMD` / `MYPY_CMD` and optional `MYPY_EXTRA_ARGS`; `bin/lint.sh` / `bin/typecheck.sh` resolve via uvx → python -m → bare.