Closes #7472

Adds an example demonstrating how to create and customize text labels on
arrows. The example covers:

- Creating arrows with labels using `toRichText()` and the `richText`
prop
- Positioning labels along the arrow path with `labelPosition` (0 =
start, 0.5 = middle, 1 = end)
- Setting independent `labelColor` distinct from the arrow's `color`
- All four font styles: `draw`, `sans`, `serif`, `mono`
- Curved arrows with `bend`

### Change type

- [x] `feature`

### Test plan

1. Run `yarn dev` and navigate to the "Arrow labels" example under
Editor API
2. Verify arrows render with correct labels, positions, colors, and
fonts
3. Verify the curved arrow displays with a bend and centered label

### Release notes

- Add arrow labels example showing how to create and customize text
labels on arrows.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Adds new example/demo code and documentation only, with no changes to
core editor behavior.
> 
> **Overview**
> Adds a new Editor API example, **Arrow labels**, that seeds the canvas
with several arrow shapes showcasing labeled arrows via
`richText`/`toRichText()`.
> 
> Demonstrates label customization including `labelPosition`,
independent `labelColor`, multiple `font` styles, and a curved (`bend`)
arrow, plus a matching `README.md` to surface the example in the
examples catalog.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
fea149b. This will update automatically
on new commits. Configure
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<!-- /CURSOR_SUMMARY -->

Closes #8100

The `ShapesWithSVGs` component (used when Debug SVG is enabled) renders
`<Shape>` without a `<ShapeCullingProvider>` ancestor. Since the `Shape`
component calls `useShapeCulling()`, this throws: "useShapeCulling must
be used within ShapeCullingProvider". The `ShapesToDisplay` component
already had this provider but `ShapesWithSVGs` was missing it.

This wraps `ShapesWithSVGs` content with `<ShapeCullingProvider>`,
`<CullingController>`, and the Safari reflow workaround — matching what
`ShapesToDisplay` already does.

### Change type

- [x] `bugfix`

### Test plan

1. Open tldraw and create some shapes on the canvas
2. Open the debug menu and enable **Debug mode**
3. Enable **Debug SVG**
4. Verify the app no longer crashes and SVG debug copies appear below
each shape

### Release notes

- Fix crash when enabling Debug SVG with shapes on the canvas.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk: localized change to canvas shape rendering that mainly
affects debug-only `Debug SVG` mode and reuses existing culling logic.
> 
> **Overview**
> Fixes a crash when enabling **Debug SVG** by ensuring shapes rendered
in that mode are wrapped in `ShapeCullingProvider` (so
`useShapeCulling()` always has a provider).
> 
> Simplifies the canvas rendering path by replacing the separate
`ShapesWithSVGs`/`ShapesToDisplay` branches with a single `ShapesLayer`
that toggles debug SVG copies internally while still running
`CullingController` and the Safari reflow workaround.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
aba4a4e. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Introduce the foundational system for shape display values — a pattern
that lets each ShapeUtil declare how its visual properties (colors,
fonts, stroke widths, etc.) are derived from shape props and theme.

- Add ShapeOptionsWithDisplayValues interface and getDisplayValues()
  helper that merges base values with user-provided overrides
- Add DEFAULT_FILL_COLOR_NAMES mapping for fill style → theme color
- Add PatternFill component to replace the pattern case from ShapeFill
- Move P3 color space detection from a React hook (useColorSpace) into
  a reactive atom on tlenvReactive, so it can be read outside React
- Update RichTextLabel and PlainTextLabel to accept resolved display
  values (fontFamily, textAlign, verticalAlign) instead of style tokens
- Remove ShapeFill (superseded by per-shape fill rendering) and
  useColorSpace (superseded by tlenvReactive.supportsP3ColorSpace)

Refactor GeoShapeUtil to derive all visual properties through display
values. This is the most complex shape — it has stroke, fill, and a
rich text label with alignment, font, and sizing configuration.

- Define GeoShapeUtilDisplayValues and GeoShapeUtilOptions interfaces
- Move label sizing, growY calculation, and shape expansion logic from
  module-level functions into private methods on the util class so they
  can access display values through this.options
- Replace direct theme/constant lookups with display value properties
- Move GeoShapeBody from components/ subdirectory to flat file,
  accepting resolved colors as props instead of reading theme internally

Refactor NoteShapeUtil to derive visual properties through display
values. The note shape is unique because its dimensions (noteWidth,
noteHeight) are themselves configurable, and several external callers
(noteHelpers, Pointing tool state) need access to those dimensions.

- Define NoteShapeUtilDisplayValues with note dimensions, background
  color, border, and label properties
- Move label sizing and font adjustment logic into private methods
- Refactor noteHelpers to accept note dimensions via options objects
  instead of importing NOTE_SIZE/NOTE_CENTER_OFFSET constants
- Update Pointing tool state to resolve note dimensions from the util

Refactor ArrowShapeUtil to derive visual properties through display
values. Arrows have stroke, fill (for arrowheads), and a label with
font, padding, and border radius configuration.

- Define ArrowShapeUtilDisplayValues interface in arrow-types.ts and
  extend ArrowShapeOptions with ShapeOptionsWithDisplayValues
- Pass resolved colors and dimensions to the ArrowSvg component as
  props instead of reading theme internally
- Update arrowLabel.ts to resolve font and padding from display values
  instead of importing constants directly
- Remove getArrowLabelFontSize (superseded by display values)

Refactor DrawShapeUtil and HighlightShapeUtil to derive visual
properties through display values.

- DrawShapeUtil: define display values for stroke color/width, fill
  color, and pattern fallback; pass resolved values to DrawShapeSvg
- HighlightShapeUtil: define display values for stroke color/width
  and opacity; move P3 color selection into getDisplayValues using
  the new tlenvReactive.supportsP3ColorSpace; move underlayOpacity
  and overlayOpacity from static options to display values

…peUtil

Refactor the remaining shape utils to derive visual properties through
display values.

- TextShapeUtil: define display values for color, font family, size,
  line height, and font style; pass resolved values to text measurement
- LineShapeUtil: define display values for stroke color and width
- FrameShapeUtil: define display values for fill, stroke, and heading
  colors in both default and showColors modes

Add empty display value implementations to shapes that don't yet have
visual properties to expose (bookmark, embed, image, video), ensuring
all built-in shapes conform to the ShapeOptionsWithDisplayValues
interface. Also wire up the EmbedShapeUtil's showShadow as a display
value.

Update SelectTool child states (PointingHandle, Translating) to resolve
note dimensions from the NoteShapeUtil's display values instead of
importing the removed NOTE_SIZE and NOTE_CENTER_OFFSET constants.

- Export all new display value types and interfaces from the tldraw
  package entry point
- Update both editor and tldraw API reports to reflect the new public
  API surface
- Add a display-options example demonstrating how to use
  getDisplayValueOverrides to customize shape rendering
- Update configure-shape-util example README to reference the renamed
  NoteShapeUtilOptions
- Update grid-align-on-create test to use inline note size constant
  instead of the removed NOTE_SIZE export