Related Issues

Follow-up to #192 / #188 — empty zAxis3D.name fixed the misleading label but dropped title framing so the metric scale looked crushed on first view.

Summary

• Grouped 3D charts keep the z-axis name for echarts-gl layout, but paint the title with transparent text so the grouping column is not shown as a height label.
• Value-mode charts still show the metric name on the vertical axis as before.
• Docs updated to describe transparent-name behavior for grouped 3D.

Changes

• Added axis3DNameInvisible() in ui/src/composables/charts/shared/3d.ts (name + nameTextStyle.color: 'transparent' only).
• Wired it into grouped mode for bar / line / scatter 3D options (replaces name: '').
• Updated useGrouped3DZAxisLabel.test.ts to assert name + transparent color.
• Updated grouped 3D docs in docs/src/content/docs/charts/3d.mdx.

Test Result

cd ui
pnpm vitest run \
  src/composables/charts/useGrouped3DZAxisLabel.test.ts \
  src/composables/charts/useScatter3DChartOptions.test.ts \
  src/composables/charts/shared/3d.test.ts

All tests passed.

Manual check (recommended):

vizb bar examples/csv/sales.csv -g product,region,category -p n,x,y --3d -o /tmp/grouped-3d.html

• Vertical axis title should not be visible
• Height scale should not look crushed on first load
• Legend still shows z group values
• Switching bar/line/scatter 3D and light/dark should not leave a sticky visible z title