## Summary
- Add JSDoc comments to undocumented props in all remaining mark
components
- Also documents the shared `RegressionMarkProps` type in the Regression
helper
- Fixes a `/*` (non-JSDoc) comment on DifferenceY's `x1` prop to use
`/**`
- Follows the same pattern established in #360, #361, #362, and #363

## Details

| Component | Props documented |
|-----------|-----------------|
| Geo | 3 props (data, geoType, svgFilter) |
| Graticule | 3 props (step, stepX, stepY) |
| BollingerX | 3 props (data, x, y) |
| BollingerY | 3 props (data, x, y) |
| BoxY | 3 props (data, x, y) |
| DifferenceY | 4 props (data, x, y, fillOpacity) |
| WaffleX | 6 props (data, x, x1, x2, y, stack) |
| WaffleY | 5 props (data, x, y, y1, y2) |
| Frame | 11 props (fill, stroke, fillOpacity, strokeOpacity, opacity,
automatic, inset, insetLeft/Right/Top/Bottom) |
| CustomMark | 11 props (data, type, x, x1, x2, y, y1, y2, r, mark,
marks) |
| CustomMarkHTML | 6 props (data, x, y, frameAnchor, class, children) |
| ColorLegend | 1 prop (class) |
| Regression helper | 5 props (x, y, type, base, span, confidence) |

**Not touched** (no new props to document):
- Sphere (inherits all from BaseMarkProps/LinkableMarkProps)
- BoxX (thin wrapper around BoxY)
- RegressionX/Y (re-export RegressionMarkProps from helper)
- SymbolLegend (no props interface)

## Test plan
- [x] `pnpm run lint` passes
- [ ] Verify hovering over component props in editor shows JSDoc

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

## Summary
- Add JSDoc comments to undocumented props in **Brush**, **Pointer**,
**HTMLTooltip**, **Vector**, **Trail**, **Spike**, and **Link** mark
components
- BrushX/BrushY are thin wrappers with no additional props to document
- Follows the same pattern established in #360, #361, and #362

## Details

| Component | Props documented |
|-----------|-----------------|
| Brush | 4 props (brush, onbrushstart, onbrushend, onbrush) |
| Pointer | 7 props (data, children, x, y, z, fx, fy) |
| HTMLTooltip | 7 props (data, x, y, r, fx, fy, children) |
| Vector | 8 props (data, x, y, r, length, rotate, shape, children,
canvas) |
| Trail | 11 props (data, x, y, z, r, curve, tension, sort, defined,
canvas, cap) |
| Spike | 6 props (data, x, y, r, length, rotate) |
| Link | 3 props (data, sort, y2) |

## Test plan
- [x] `pnpm run lint` passes
- [ ] Verify hovering over component props in editor shows JSDoc

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>