docs(changelog): quote the MEASURED CI number, not the local one

The first commit quoted a local 4-CPU-pinned A/B (326s -> 109s, 2.98x). CI has now run
this branch and realizes less: the `test-polars (3.12)` cell goes 501s -> 322s and its
script step 484s -> 297s (1.63x), with the five non-coverage cells at 222-318s -> 115-172s.

Coverage tracing is per-worker CPU cost that does not parallelize away, and the ~8s serial
second phase plus 4x interpreter startup are fixed, so the coverage cell gains less than
the plain cells (which see ~2x). The CI figure is the one that decides whether #1805 fits,
so it is the one the changelog quotes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015YsqAZQLbqjSDrYSFz2GoB

Author: lmeyerov

CHANGELOG.md

@@ -37,7 +37,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - **Seeded property-RETURN dtype divergence on cuDF**: the lean projection applied the pandas rows-pivot artifact (int → float64, bool → object) on every engine, but cuDF's canonical pivot preserves the source dtypes — so the fast path returned `float64`/`object` where cuDF's own canonical path returns `int64`/`bool`. The cast rule is now engine-aware; the dtype-class decline guard is unchanged.
 
 ### Infrastructure
-- **The polars CI lane runs in parallel, so the coverage cell stops racing its timeout**: `test-polars (3.12)` is the only cell that runs the coverage-instrumented pass *and* the per-file coverage audit, and it had already been cancelled twice at its 10-minute budget (615s, 611s) with zero test failures — pure budget exhaustion, with the same commit passing or failing depending on the runner it drew. `bin/test-polars.sh` now runs its main phase under `pytest-xdist` (`-n auto --maxprocesses 4 --dist load`); `pytest-xdist` was already in the `[test]` extra and `test-gfql-core` already runs `-n auto` under `--cov`, so no dependency changes. `auto` resolves to the runner's core count (4 on a GitHub-hosted `ubuntu-latest`) and scales *down* on a 2-vCPU runner where a fixed `-n 4` could be slower than serial; `--maxprocesses` keeps a many-core dev box from fanning out one polars process per core. Verified rather than assumed, on py3.12 / polars 1.43.1 / pandas 3.0.5 with `POLARS_COV=1`: the pass/skip **node-id sets** (not just counts) are identical serial vs parallel across 4-worker, 2-worker and `--dist loadfile` runs (2417 node ids, 2404 passed / 13 skipped every time); the merged coverage data is a strict superset of the serial data (28,480 vs 28,478 covered lines, zero lines lost, zero files dropped); the second `--cov-append` invocation still appends into the xdist-produced data file (+1,791 lines, nothing lost); and `bin/coverage_audit.py --profile gfql-polars` emits a byte-identical report (modulo its timestamp) from the parallel data, so the downstream `changed-line-coverage` check sees no change. Measured lane wall-clock with coverage on: **354s serial → 112s parallel (3.2×)**. `--dist load` rather than `loadfile` because one module (`test_engine_polars_chain.py`) is 69% of the lane's test time, capping file-level distribution at ~1.4×; `POLARS_XDIST=0` restores the serial path and `POLARS_XDIST_DIST` selects another distribution mode should a future order-dependent test need one.
+- **The polars CI lane runs in parallel, so the coverage cell stops racing its timeout**: `test-polars (3.12)` is the only cell that runs the coverage-instrumented pass *and* the per-file coverage audit, and it had already been cancelled twice at its 10-minute budget (615s, 611s) with zero test failures — pure budget exhaustion, with the same commit passing or failing depending on the runner it drew. `bin/test-polars.sh` now runs its main phase under `pytest-xdist` (`-n auto --maxprocesses 4 --dist load`); `pytest-xdist` was already in the `[test]` extra and `test-gfql-core` already runs `-n auto` under `--cov`, so no dependency changes. `auto` resolves to the runner's core count (4 on a GitHub-hosted `ubuntu-latest`) and scales *down* on a 2-vCPU runner where a fixed `-n 4` could be slower than serial; `--maxprocesses` keeps a many-core dev box from fanning out one polars process per core. Verified rather than assumed, on py3.12 / polars 1.43.1 / pandas 3.0.5 with `POLARS_COV=1`: the pass/skip **node-id sets** (not just counts) are identical serial vs parallel across 4-worker, 2-worker and `--dist loadfile` runs (2417 node ids, 2404 passed / 13 skipped every time); the merged coverage data is a strict superset of the serial data (28,480 vs 28,478 covered lines, zero lines lost, zero files dropped); the second `--cov-append` invocation still appends into the xdist-produced data file (+1,791 lines, nothing lost); and `bin/coverage_audit.py --profile gfql-polars` emits a byte-identical report (modulo its timestamp) from the parallel data, so the downstream `changed-line-coverage` check sees no change. Measured **on CI**, by this change's own run: the `test-polars (3.12)` cell goes **501s → 322s**, its script step **484s → 297s (1.63×)**, and the five non-coverage cells go 222–318s → 115–172s. (A local 4-CPU-pinned A/B with coverage on showed 326s → 109s, 2.98×; CI realizes less, because coverage tracing is per-worker CPU cost that does not parallelize away and the ~8s serial second phase plus 4× interpreter startup are fixed. The CI number is the one to quote.) `--dist load` rather than `loadfile` because one module (`test_engine_polars_chain.py`) is 69% of the lane's test time, capping file-level distribution at ~1.4×; `POLARS_XDIST=0` restores the serial path and `POLARS_XDIST_DIST` selects another distribution mode should a future order-dependent test need one.
 
 ### Documentation
 - **GFQL pay-as-you-go resident indexing user guide**: New :doc:`Pay-As-You-Go Resident Indexing <gfql/indexing>` page — the lifecycle guide to resident indexes (`gfql_index_all()` / `gfql_index_edges()` / `create_index()` / `show_indexes()` / `drop_index()`): what the node-id + CSR in/out adjacency sidecars are, what engages them on 0.58.0 (seeded typed-hop fast paths incl. property RETURNs and property-seeded lookups per #1768/#1770, direct `g.hop()`; the general polars chain traversal honestly noted as not yet covered), the staleness/validity contract (identity + fingerprint; rebind invalidates; declines are safe — identical results either way), engine notes (polars needs `gfql_index_all(engine='polars')` until #1767), 0.58.0-tag measured numbers, and a runnable end-to-end example. Wired into the GFQL toctree + recommended paths alongside :doc:`Seeded Traversal Indexes <gfql/index_adjacency>`.