M3: paint: colour profiles (Display P3), image adjustment presets, style picker (#54)

* M3: colour profiles: sRGB or Display P3 per file, convert or keep values, tagged exports

- color: ColorProfile (srgb, displayP3) with conversions derived from the primaries (shared D65
  white and sRGB curve; out-of-gamut channels clip), table-driven pixel conversion, a generated
  ICC v4 matrix/TRC profile and PNG cICP code points.
- doc: Document.color_profile (serde default sRGB, written only when set); every colour value
  (paints, text runs, effects, grids, page and prototype backgrounds, overlay backdrops, styles,
  colour variables, document colours) can be mapped; set_color_profile converts or reinterprets.
- engine: file.colorProfile {profile?, convert?} (File > Color profile...; without a profile it
  opens the dialog); document.inspect reports colorProfile.
- render: images are taken as sRGB and managed into the file's space; encode_export tags PNG
  (sRGB chunk, or iCCP + cICP for Display P3) and embeds the ICC profile in Display P3 JPG/WebP;
  SVG and PDF export Display P3 files converted to sRGB. The CLI exports the same way.
- ui: Color profile dialog (keep appearance / keep values) and a Color profile row on the page
  panel; the canvas, presenter, thumbnails, swatches and colour picker show a Display P3 file's
  colours converted to the screen's sRGB, and Copy as PNG converts too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* M3: image adjustment presets: built-in, saved in the file, reset

- color: ImageFilters::PRESETS (Vivid, Muted, Warm, Cool, Black & white, Fade, Reset), lookup by
  id or label, and sanitized values.
- doc: Document.image_presets (name + adjustments; written only when there are some).
- engine: image.adjust {ids?, target?, index?, preset?, filters?} sets the adjustments of image
  paints from a preset (built-in or saved) with values on top, one undo step; image.savePreset,
  image.deletePreset and image.presets.
- ui: the colour picker's image section gets a presets menu named after the preset in effect
  ("Custom" otherwise), saved presets with delete, "Save as preset...", a Reset button, and
  aligned adjustment sliders.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* M3: style picker: search, folders, list or swatch grid, edit, create, detach

The Fill, Stroke, Effects and Layout grid sections' Styles button opens a popover laid out like
the variable picker (crates/ui-egui/src/style_picker.rs):

- search over style names; styles grouped by the folders of their `/`-separated names, which
  collapse (searching opens them); colour styles as a list or a grid of swatches;
- click applies, a check marks the applied style; the row's edit button (or a right-click) edits
  the name, description and values: colour style paints open the colour picker on the style,
  effect and grid styles update from the selection; delete;
- `+` creates a style from the selection's current values and opens it for naming; detach;
- colour slots still list colour variables to bind;
- the applied style chip opens the picker; new icons Adjust, ViewList, ViewGrid (drawn in code);
- control channel: ui.set {stylePicker, stylePickerEdit, stylePickerView}.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

apps/figcraft-cli/src/files.rs

@@ -84,13 +84,10 @@ pub fn render_page(doc: &Document, page: NodeId, scale: f64) -> CliResult<figcra
     figcraft_render::render_view(doc, page, &view, &Default::default()).ok_or_else(|| CliError::Failed("render failed".into()))
 }
 
-fn encode(pix: &figcraft_render::Pixmap, e: &str) -> CliResult<Vec<u8>> {
-    match e {
-        "jpg" | "jpeg" => figcraft_render::encode_jpeg(pix, figcraft_doc::color::Color::WHITE, 90),
-        "webp" => figcraft_render::encode_webp(pix),
-        _ => figcraft_render::encode_png(pix),
-    }
-    .map_err(CliError::Failed)
+/// Encode a render as the format extension `e` names, tagged with `doc`'s colour profile.
+fn encode(doc: &Document, pix: &figcraft_render::Pixmap, e: &str) -> CliResult<Vec<u8>> {
+    let format = ExportFormat::from_ext(e).unwrap_or_default();
+    figcraft_render::encode_export(pix, format, doc.color_profile).map_err(CliError::Failed)
 }
 
 /// Write `doc` to `out`, choosing the format by extension.
@@ -105,10 +102,10 @@ pub fn write_doc(doc: &Document, page: NodeId, out: &str) -> CliResult<()> {
             let v = figcraft_format::to_json(doc).map_err(|e| CliError::Failed(e.to_string()))?;
             serde_json::to_vec_pretty(&v).map_err(|e| CliError::Failed(e.to_string()))?
         }
-        "svg" => figcraft_svg::export_svg(doc, &children(doc, page), &Default::default())
+        "svg" => figcraft_svg::export_svg(&doc.in_srgb(), &children(doc, page), &Default::default())
             .ok_or_else(|| CliError::Failed("the page is empty: nothing to export".into()))?
             .into_bytes(),
-        "png" | "jpg" | "jpeg" | "webp" => encode(&render_page(doc, page, 1.0)?, &e)?,
+        "png" | "jpg" | "jpeg" | "webp" => encode(doc, &render_page(doc, page, 1.0)?, &e)?,
         "pdf" => figcraft_engine::cmd::file::export_bytes(doc, &children(doc, page), ExportFormat::Pdf, 1.0)
             .map_err(|e| CliError::Failed(e.to_string()))?,
         other => return Err(CliError::Usage(format!("unknown output format `.{other}` (figcraft, json, svg, png, jpg, webp, pdf)"))),
@@ -242,7 +239,7 @@ pub fn render(file: &str, out: &str, scale: f64, page: Option<&str>) -> CliResul
         return Err(CliError::Usage(format!("render writes .png, .jpg or .webp, not `{out}`")));
     }
     let pix = render_page(&doc, page, scale)?;
-    write(out, &encode(&pix, &e)?)?;
+    write(out, &encode(&doc, &pix, &e)?)?;
     println!("{out} ({}×{})", pix.width(), pix.height());
     Ok(ExitCode::SUCCESS)
 }