Fix #508: PDF/.ai import keeps type strokes, wrapped lines and layer order

- Type left unfinished when a layer's marked content ends, and a clip that closes in a later layer,
  stay in their own layer (no stray "Page N" layer, no art moved to the next layer).
- Top-level layers stack as the pages mark them, so a layer whose art starts on a later page keeps its
  place; layers marked with no art come in empty.
- A stroke written as each glyph's outline stroked, right after (or before) the type, becomes the type
  object's stroke above (or below) its characters: the type stays one editable object.
- Spaces read from gaps wider than a space get their own tracking where even tracking would put the
  glyphs after them more than a tenth of an em off (barcode digit groups); lines are measured to their
  last visible glyph, so a wrapped line's trailing space no longer spreads into the tracking.
- Lines wrapped in a frame (each wrapped line ending in a space, one left edge, font, size and leading,
  with an optional paragraph spacing) come back as one area type object, left aligned or justified,
  only where laying it out breaks the lines exactly where the file does.

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

crates/engine/src/cmd/fileio/mod.rs

@@ -78,7 +78,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Open Document",
             [],
             None,
-            "{path} or {name, dataBase64}, PDF/.ai: pages?: \"2-3, 5\" (1-based, default all; one artboard each) | page?: n, cropTo?: bounding|art|crop (default)|trim|bleed|media (the box each artboard gets; bounding: the art's bounds), password? (encrypted PDFs; see document.pdfInfo), textAs?: text (default: point type per line, in the file's fonts by name; missing ones are listed in warnings) | outlines (glyph paths), layers?: true (default: optional content groups become layers with their visibility, print state and lock — art that is off comes in as a hidden layer; other art goes to a layer per page) | false (one layer per page, without the art that is off; Save then asks for a name), colorMode?: rgb|cmyk (the mode the document opens in, its colours converted as file.documentColorMode does, grays? as there; default: the file's — a PDF keeps CMYK, Gray and spot inks (spot swatches at a tint) and opens in CMYK when painted mostly in CMYK), DXF: dxf?: {layout?: \"Model\" (default) | a paper layout's name (document.dxfInfo lists them), unit?, scale? (the ratio: 1 unit of the art = scale drawing units; default: the drawing at 1:1 in its own unit), fit?: false (scale to fit an artboard of fitTo?: [612, 792], turned to the art's orientation), scaleLineweights?: false (lineweights scale with the art), center?: true (false: the drawing's origin on the artboard's bottom-left corner; fitted art's bottom-left corner), mergeLayers?: false (all art on one layer)} → {index, title, format, warnings, restored, missingLinks, modifiedLinks, updatedLinks: [{name, path, ids}]}; any readable format (see document.formats): .vectorcraft/.drawcraft, .svg/.svgz, .pdf/.ai, .ait, ASCII .dxf (each DXF layer with art a layer; blocks symbols; what can't come in is listed in warnings), PNG/JPEG/GIF/WebP/TIFF/BMP (an image opens as a document of its pixel size), .emf/.wmf (one artboard, the picture's frame; records VectorCraft doesn't read are skipped with one warning), .eps and PostScript .ai (one artboard, the bounding box: an EPS file VectorCraft wrote restores the document it carries, restored: true; other files are read by a PostScript interpreter — paths, colours and spot inks, clips, gradients, images, type in the fonts named — and come in as their TIFF preview, with a warning, when their PostScript can't be read). A PDF/.ai/.ait or SVG saved with Preserve Editing restores the native document it carries (restored: true; a PDF only when no pages are picked), unless the file was changed elsewhere since or the data can't be read: then its artwork is imported and the first warning says why. Templates (native templates, .ait) open as a new untitled document; a restored .ai keeps its path (Save writes .ai again). Linked images are read from their files (looked for at their path, then relative to the document): missing ones show their saved preview (links.relink), modified ones are read again only with Preferences › Update Links: Automatically (else links.update). An SVG's <image> files (relative links from the SVG's folder) stay linked, SVG files become art, missing ones a placeholder in their box (a warning and missingLinks)",
+            "{path} or {name, dataBase64}, PDF/.ai: pages?: \"2-3, 5\" (1-based, default all; one artboard each) | page?: n, cropTo?: bounding|art|crop (default)|trim|bleed|media (the box each artboard gets; bounding: the art's bounds), password? (encrypted PDFs; see document.pdfInfo), textAs?: text (default: point type per line, lines wrapped in a frame as area type where they lay out the same, in the file's fonts by name; missing ones are listed in warnings) | outlines (glyph paths), layers?: true (default: optional content groups become layers with their visibility, print state and lock — art that is off comes in as a hidden layer; other art goes to a layer per page) | false (one layer per page, without the art that is off; Save then asks for a name), colorMode?: rgb|cmyk (the mode the document opens in, its colours converted as file.documentColorMode does, grays? as there; default: the file's — a PDF keeps CMYK, Gray and spot inks (spot swatches at a tint) and opens in CMYK when painted mostly in CMYK), DXF: dxf?: {layout?: \"Model\" (default) | a paper layout's name (document.dxfInfo lists them), unit?, scale? (the ratio: 1 unit of the art = scale drawing units; default: the drawing at 1:1 in its own unit), fit?: false (scale to fit an artboard of fitTo?: [612, 792], turned to the art's orientation), scaleLineweights?: false (lineweights scale with the art), center?: true (false: the drawing's origin on the artboard's bottom-left corner; fitted art's bottom-left corner), mergeLayers?: false (all art on one layer)} → {index, title, format, warnings, restored, missingLinks, modifiedLinks, updatedLinks: [{name, path, ids}]}; any readable format (see document.formats): .vectorcraft/.drawcraft, .svg/.svgz, .pdf/.ai, .ait, ASCII .dxf (each DXF layer with art a layer; blocks symbols; what can't come in is listed in warnings), PNG/JPEG/GIF/WebP/TIFF/BMP (an image opens as a document of its pixel size), .emf/.wmf (one artboard, the picture's frame; records VectorCraft doesn't read are skipped with one warning), .eps and PostScript .ai (one artboard, the bounding box: an EPS file VectorCraft wrote restores the document it carries, restored: true; other files are read by a PostScript interpreter — paths, colours and spot inks, clips, gradients, images, type in the fonts named — and come in as their TIFF preview, with a warning, when their PostScript can't be read). A PDF/.ai/.ait or SVG saved with Preserve Editing restores the native document it carries (restored: true; a PDF only when no pages are picked), unless the file was changed elsewhere since or the data can't be read: then its artwork is imported and the first warning says why. Templates (native templates, .ait) open as a new untitled document; a restored .ai keeps its path (Save writes .ai again). Linked images are read from their files (looked for at their path, then relative to the document): missing ones show their saved preview (links.relink), modified ones are read again only with Preferences › Update Links: Automatically (else links.update). An SVG's <image> files (relative links from the SVG's folder) stay linked, SVG files become art, missing ones a placeholder in their box (a warning and missingLinks)",
             always,
             load::open
         ),