Part of #978: Window › Color Wheel picks colors on a hue ring and a saturation and brightness square

Window › Color Wheel opens a new panel: the Fill and Stroke proxy
beside a hue ring around a square with saturation across and
brightness up at the ring's hue. It edits what the Color panel's
sliders edit (the active proxy's color, the selected gradient stop or
freeform point) through the same paint commands, and a drag is one
undo step. Alt paints the other proxy, and Shift steps the ring by
45°. The Color panel does not change.

A pick is display sRGB and goes into the working RGB space through the
color settings. An RGB, CMYK or Lab color keeps its model, and a Gray
color or a tint of a global swatch becomes a process color in the
document's color mode. The wheel keeps the hue of the last pick while
the objects, the proxy and the color are unchanged, so a drag through
a gray and back keeps the hue.

A press gives the ring or the square the keyboard focus. The arrow
keys then step the hue by 1° or the saturation and brightness by 1%.
With Shift a press steps ten times as far, and with Cmd/Ctrl it steps
a tenth as far. Each press makes one undo step, and Escape or a click
elsewhere gives the keys back to the tools. Screen readers
read the ring as a slider from 0 to 360 with increment, decrement and
set-value actions, and the square as its name and both values. The
Color Picker's color field is the same widget, so it takes the same
keys and reports its name and values.

Color::to_hsb and Color::from_hsb now call the new rgb_to_hsb and
hsb_to_rgb, which the panel uses on display sRGB numbers.

docs/control-protocol.md

@@ -246,6 +246,11 @@ Color Themes panel (`window.panel {panel: "colorThemes"}`): its Create tab makes
 My Themes tab lists the saved themes; every action runs a command (`colorTheme.save`, `colorTheme.delete`,
 `colorTheme.addToSwatches`, `swatch.newGroup` for the theme being made), and `colorTheme.list` reads the library.
 
+Color Wheel panel (`window.panel {panel: "colorWheel"}`): a hue ring around a saturation and brightness square. A
+pick runs the commands the Color panel's sliders run: `paint.setFill` or `paint.setStroke` with `keepModel`,
+`paint.editGradient` for a gradient's selected stop, and `paint.freeform.setPoint` for a freeform gradient's selected
+point (the first stop or point when none is selected).
+
 Edit Colors dialogs: `ui.colorBalanceDialog` opens Adjust Colors (`colorBalance`: fields `mode` `gray`/`rgb`/`cmyk`/
 `global`, the channels `r` `g` `b` / `c` `m` `y` `k` / `gray` / `tint` (global mode) from −100 to 100, `convert`, `fill`, `stroke`,
 `preview`) and `ui.saturateDialog` opens Saturate (`saturate`: `intensity` −100..100, `preview`). Both preview on the

docs/target-app-parity.md

@@ -1186,6 +1186,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   - **Colorized images (#1466):** a fill color applied to a selected grayscale or 1-bit image (`paint.setFill`) colorizes it with black, white, a process color or a spot color, and refuses a process color when the image has an alpha channel ([Convert color modes](https://web.archive.org/web/20251220223850/https://helpx.adobe.com/illustrator/desktop/manage-colors/select-and-adjust-colors/convert-color-modes.html), "Colorize Grayscale or 1-bit images"); black and white are accepted there too. The canvas draws each pixel in the color as far as the pixel is dark, with white pixels transparent; PDF export writes the image in the color (a spot color as its ink, Registration in every ink) with the image as its soft mask; Separations Preview and printed separations show it on its color's plates; native files keep the color. EPS and SVG write the image's own pixels.
   - **Missing library files:** a persistent swatch or graphic style library panel whose file is gone at startup reopens and stays in the preferences, showing the file's path with Locate Library… (`ui.libraryPanel.locate`), which reads the file from where it is now into the same panel.
   - **Swatch library and Recolor Artwork parameters:** the `swatch.library.*` commands, `swatch.resetDefaults`, the graphic style library save, load and add, the `recolor.*` commands and `color.harmony`'s `limitTo` refuse parameters of the wrong form, such as `names: "Grays"`, `limitTo: 5` or `includeImages: "false"`. Errors name the parameter, except that a `limitTo` that is not a string, such as `5`, gets an unknown-library error. A `null` counts as left out except for `recolor.apply`'s `model`, which must be a string when given.
+  - **Color Wheel panel (part of #978):** Window › Color Wheel shows the Fill and Stroke proxy beside a hue ring around a square with saturation across and brightness up. It edits what the Color panel's sliders edit (the active proxy's color, the selected gradient stop or freeform point) through the same paint commands, and a drag is one undo step. Alt paints the other proxy, and Shift steps the ring by 45°. A pick goes from display sRGB into the working RGB space; an RGB, CMYK or Lab color keeps its model, and a Gray color or a tint of a global swatch becomes a process color in the document's color mode. A click gives the ring or the square the keyboard focus, and the arrow keys then step the color; both report their names and values to screen readers, and the Color Picker's color field takes the same keys.
   - **Colour:** a Color Picker (colour field, H/S/B/R/G/B channel slider, HSB/RGB/Lab/CMYK fields, hex, web-only snapping, out-of-gamut correction); the Color panel shows a selected colour in its own model and, with nothing selected, the new-art defaults in the mode picked last, which it keeps between sessions; Alt-click paints the other proxy; proxies look through groups and show "?" for mixed paint; Invert, Complement, Apply Last Color (`,`) and Apply Last Gradient (`.`) keep the colour model; every paint command feeds the recent colours. The Color Guide has 21 harmony rules, Steps and Variation options and Limit to Library. Adjust Color Balance (its Global mode shifts tints) and Saturate preview live; Edit Colors and Recolor also reach meshes, images and patterns. Recolor Artwork has colour reduction, five recolour methods, presets, Limit to Library, a colour-wheel Edit tab and Edit Color Group; a local Color Themes panel saves five-colour themes. Fill/Stroke chips open swatch and mixer popovers (the Properties panel has the Control bar's Fill and Stroke chips, Stroke link and weight spinner, with nothing selected too), panels have Illustrator's Window menu keys (Align Shift+F7, Transform Shift+F8, Pathfinder Cmd+Shift+F9, Layers F7, Character Cmd+T…; every panel can be given one in Edit › Keyboard Shortcuts), and Eyedropper Options pick up and apply chosen attributes (Alt and Shift+Alt, image pixels). An ICC CMYK profile converts straight into the RGB working space (not through sRGB, so a wider space such as Wide Gamut RGB keeps colours sRGB can't hold) with the colour settings' black-point compensation, on the canvas and in RGB exports alike (the built-in Generic CMYK compensates both ways, so RGB black separated to a rich black displays as black again). Fills and strokes can overprint (Attributes panel, Overprint Black options), and CMYK documents blend in inks on screen, in PDF and when flattening. Document Color Mode converts the art, symbols, pattern tiles and swatches through the colour settings: Gray stays Gray, RGB grays separate into light grays in cyan, magenta and yellow only, darker four-color grays and a rich black, or go on the black plate only with `grays: "black"` (also for `document.open {colorMode}`).
     Plain Comma and Period, and also Shift+Comma and Shift+Period, apply the last solid color and the last gradient to the active Fill or Stroke proxy in VectorCraft ([Default keyboard shortcuts](https://web.archive.org/web/20260726060015/https://helpx.adobe.com/illustrator/using/default-keyboard-shortcuts.html), "Select color fill mode" and "Select gradient fill mode").
     Recent Colors keeps the last 30 solid colors applied, newest first and each once, and the list stays the same when another document is opened or made active; a 31st color drops the oldest ([Select colors using the Color panel](https://helpx.adobe.com/illustrator/desktop/manage-colors/select-and-adjust-colors/select-colors-using-the-color-panel.html)). The list lasts for the session. In the Color and Swatches panels the chips wrap onto further rows when the panel is too narrow for one row (`paint.recent`). Tests: `recent_colors_keep_thirty_colors_across_documents` in `crates/engine/src/tests/paintproxy.rs`, `all_thirty_recent_colors_wrap_into_a_narrow_panel` in `crates/ui-egui/src/panels/color/tests.rs`.