Color management: documents behind the front one draw through their own profiles

With Window › Arrange › Tile or floating document windows, every document
other than the front one was drawn through the profiles the front document
is assigned, since the active color settings are process-wide.

- cms::with_active puts other settings in place of the active ones on one
  thread, fast paths included, and puts them back after (also on a panic).
  cms::for_document gives the context a document's assigned profiles make,
  the same one each time for the same profiles and working settings.
- Each pane renders its document's art through colormgmt::doc_cms, on the
  render worker and on the UI thread alike, and draws its paper, artboard
  colors and transparency grid through the same settings.
- Loading or removing a profile redraws the documents assigned it, the
  ones behind the front one included.
- The ink and separation tables keep the tables of up to four color
  settings, so documents with different CMYK profiles side by side do not
  rebuild them on each redraw.

Placed documents inside a document behind the front one still draw through
the front document's profiles.

docs/target-app-parity.md

@@ -727,7 +727,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
 - **Document Setup › Color:** a Color tab shows the document color mode (RGB Color or CMYK Color), a Convert to CMYK or Convert to RGB box for a mode change (cleared: the colors keep their numbers), and the RGB and CMYK profiles assigned to the document, with a working-space entry for none. OK runs `edit.assignProfile` and then `file.documentColorMode` with the dialog's other changes in one `command.batch`, and the document's changes are one undo step. An unchanged Color tab adds no color commands, and Cancel, or OK with nothing changed, records no undo step. A Color tab field with a value of the wrong kind is an error, and the dialog stays open. The tab is VectorCraft's own layout; File › Document Color Mode and Edit › Assign Profile… stay as they are. Tests in `dialogs/document_setup.rs`.
 - **Canvas through the display's profile on Windows and X11:** Preferences › Performance › Use Monitor Profile for Canvas (on by default) converts the canvas's art, artboard paper and transparency grid from sRGB into the ICC profile of the display that shows most of the main window, after any proof, as the help page describes the monitor's profile translating the document's colors for the monitor ([the help page](https://help.adobe.com/archive/en_US/illustrator/cs4/illustrator_cs4_help.pdf#page=151)). Windows gives the display's default profile, and a display with Advanced Color on is left to Windows ([Microsoft Learn](https://learn.microsoft.com/en-us/windows/win32/wcs/advanced-color-icc-profiles)); X11 gives colord's profile for the output or the `_ICC_PROFILE` property. macOS converts the window itself, and a Wayland session stays sRGB. `ui.inspect` reports `displayProfile`. Tests in `color/src/cms/display.rs`, `ui-egui/src/display_profile.rs` and `canvas::tests::the_canvas_is_drawn_through_the_display_profile_while_the_preference_is_on`.
 - **Out-of-gamut warning after a profile change:** the out-of-gamut warning and its closest-color correction in the Color panel and Color Picker ([the help page](https://helpx.adobe.com/illustrator/using/adjusting-colors.html)) check the color against the document's assigned CMYK profile, else the working CMYK space, and update when Edit › Assign Profile… or Edit › Color Settings… changes that space or a loaded profile changes, without a change of color. Which CMYK space the warning uses is VectorCraft's own rule. Tests: `gamut_warning_follows_a_profile_change` and `gamut_warning_follows_a_profile_loaded_again` in `dialogs/color_picker/tests.rs`.
-- **Assign Profile and the working spaces:** Edit › Assign Profile… tags the document and leaves the working spaces of Edit › Color Settings… as they are, in Color Settings, the Separations panel and the settings saved for the next start. Colors show and convert through the profiles assigned; a change in Color Settings keeps the profiles the document in front is assigned in use, and removing an assigned profile in use puts the working space back in its place. The profiles in use follow the document in front: a new, opened or reverted document, a switch to another tab, a close, Undo and Redo of Assign Profile, a failed batch, each step of a batch, Export All Open and the update of placed documents put that document's profiles in use, and the working spaces where it is assigned none or no document is open. View › Proof Setup › Working CMYK simulates the working CMYK space of Color Settings in Proof Colors and Separations Preview, also in a document assigned another CMYK profile. Public references: [Changing the color profile for a document and About color working spaces](https://help.adobe.com/archive/en_US/illustrator/cs3/illustrator_cs3_help.pdf#page=150) and [Soft-proof presets](https://help.adobe.com/archive/en_US/illustrator/cs3/illustrator_cs3_help.pdf#page=134). Tests in `engine/tests/color_settings.rs`.
+- **Assign Profile and the working spaces:** Edit › Assign Profile… tags the document and leaves the working spaces of Edit › Color Settings… as they are, in Color Settings, the Separations panel and the settings saved for the next start. Colors show and convert through the profiles assigned; a change in Color Settings keeps the profiles the document in front is assigned in use, and removing an assigned profile in use puts the working space back in its place. The profiles in use follow the document in front: a new, opened or reverted document, a switch to another tab, a close, Undo and Redo of Assign Profile, a failed batch, each step of a batch, Export All Open and the update of placed documents put that document's profiles in use, and the working spaces where it is assigned none or no document is open. With Window › Arrange › Tile or floating document windows, each document behind the front one draws its art, paper and transparency grid through its own assigned profiles, and loading or removing a profile redraws the documents assigned it; placed documents inside it still draw through the front document's profiles. How documents behind the front one draw is VectorCraft's own rule. View › Proof Setup › Working CMYK simulates the working CMYK space of Color Settings in Proof Colors and Separations Preview, also in a document assigned another CMYK profile. Public references: [Changing the color profile for a document and About color working spaces](https://help.adobe.com/archive/en_US/illustrator/cs3/illustrator_cs3_help.pdf#page=150) and [Soft-proof presets](https://help.adobe.com/archive/en_US/illustrator/cs3/illustrator_cs3_help.pdf#page=134). Tests in `engine/tests/color_settings.rs`.
 - **New Document's More Settings and Save Preset:** More Settings opens a pop-up over New Document with only Number of Artboards, the artboard layout, Change to Right-to-Left Layout, Spacing and Columns; Done, Escape or a click outside closes it and keeps the values. Save Preset turns the top of Preset Details into a Save Document Preset heading with the preset's name, Cancel and Save, and hides the document's name, Close and Create until the preset is saved or canceled; nothing in that mode creates a document. Save Preset's default name is the first "Preset N" no saved preset has. VectorCraft's own layout. Harness tests in `dialogs/new_document.rs` cover both.
 - **New Document profiles:** each built-in category's presets start documents from that category's profile, a native document holding the starting swatches, graphic styles, brushes, symbols and other assets, the ruler and Document Setup options and the print settings ([Create a custom new document profile](https://helpx.adobe.com/illustrator/desktop/add-and-import-files/start-a-new-file/create-a-custom-new-document-profile.html)). New Document's Manage Profiles pop-up opens a profile to edit and resets one to the shipped profile (`file.newProfiles`, `file.newProfiles.edit`, `file.newProfiles.reset`; `file.new {profile}`). The profiles live in VectorCraft's own `New Document Profiles` folder next to the preferences; a profile that cannot be read or is larger than 64 MiB leaves the defaults and is reported. Tests: `tests::newdoc::an_edited_profile_starts_the_documents_of_its_category`, `the_profile_follows_the_preset_access_and_reset`, `profile_errors_name_the_file_by_its_name_outside_the_read_roots`, `a_damaged_or_oversized_profile_leaves_the_defaults_and_is_reported`, `profile_names_are_checked_and_editing_needs_the_folder`, `dialogs::new_document::tests::manage_profiles_edits_and_resets_the_profiles`.
 - **Control bar with the Artboard tool:** while the Artboard tool is in use, the Control bar shows the active artboard's controls in place of the object controls: Preset, Portrait and Landscape, New Artboard, Delete Artboard, the Name field, Artboard Options, Rearrange All Artboards, the Transform link, Move and Scale Artwork with Artboard and, while the bar has room, the reference point with X and Y, and W and H with the Constrain Width and Height Proportions link. Each runs the command its Properties or Transform panel counterpart runs (`artboard.setProps`, `artboard.new`, `artboard.delete`, `tool.options {tool: "artboard"}`), and the reference point is the one the Transform panel uses. In an 800-point window the controls up to the Transform link fit, Move and Scale Artwork with Artboard show as their boxes alone with their names in tooltips, and the link opens the Transform panel with the artboard's position and size. Pointer and key tests in `panels/artboards.rs` cover the controls, W about the reference point, the orientation and the name. Public reference: [Using multiple artboards](https://web.archive.org/web/20210925094818/https://helpx.adobe.com/illustrator/using/using-multiple-artboards.html) (archived copy).