Adding any focus mark removes the built-in focused-point ring from the whole chart

[dschoent]

Version: @tanstack/charts 0.4.0

Repro

1. A chart with lineY + the tooltip extension: hovering shows the default focus ring (the --ts-chart-focus-fill circle) on the nearest point. ✅
2. Add any whenFocused(...) mark to the same definition — e.g. a focused band straight from the docs example:

marks: [
  whenFocused(bandX(dates, { x: "date", fillOpacity: 0.14 }), { match: "x" }),
  lineY(rows, { x: "date", y: "value", color: "series" }),
],

3. The focused-point ring is now gone everywhere — hover and keyboard navigation no longer highlight which point the tooltip refers to.

Why

In scene.js, the default focus layer is only built when no focus marks exist:

const hasFocusMarks = initialized.some((mark) => mark.focus)
// ...
if (!hasFocusMarks && points.length) { /* build default-focus layer */ }

So opting into one decorative focus mark silently opts the chart out of the built-in point highlight.

Expected

The default ring persists alongside author-supplied focus marks (they serve different purposes: decoration at the focused x vs. identifying the focused point), or an explicit definition-level option to disable it — but not an implicit all-or-nothing.

Context

Hit while adding a crosshair focus mark: dense multi-series charts lost the "which point is the tooltip about?" affordance. Worked around by recreating the ring as whenFocused(dot(rows, {..., r: 5}), { match: "primary" }) per mark group.