ci(mac-native): tolerance sidecar for chart-transform Metal AA noise

ChartTransform draws its latency line and axes as antialiased diagonals
via Graphics.setTransform. Metal antialiases those edges slightly
differently between mac CI runners -- measured ~0.23% of pixels over
channelDelta 8 (max single-channel delta ~86 on a line edge) while the
chart content is byte-for-byte the same shape. The other mac-native
theme goldens were reseeded already, leaving this as the lone strict
CN1SS_FAIL_ON_MISMATCH=1 failure. Add a per-test .tolerance sidecar
(maxChannelDelta=8, maxMismatchPercent=3.0) mirroring the Gpu3D* sidecars
so sub-pixel GPU noise no longer fails the build.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: shai-almog

scripts/mac-native/screenshots/chart-transform.tolerance

@@ -0,0 +1,8 @@
+# ChartTransform renders a chart through Graphics.setTransform, so the latency
+# line and axes are drawn as antialiased diagonals. Metal antialiases those
+# edges slightly differently between mac CI runners (measured ~0.23% of pixels
+# over channelDelta 8, max single-channel delta on a line edge ~86) while the
+# chart content is otherwise identical. Widen tolerance so this sub-pixel GPU
+# noise does not fail the build -- same approach as the Gpu3D* sidecars.
+maxChannelDelta=8
+maxMismatchPercent=3.0