PDF export: PDF and .ai files carry File Info's copyright status, notice and URL

The PDF writer's metadata has no copyright fields, so the XMP packet of
PDF exports and PDF-compatible .ai and .ait saves left out File Info's
copyright status, notice and URL. A PDF exported without its editing
data opened with the status Unknown and an empty notice and URL,
although the reader takes them from dc:rights, xmpRights:WebStatement
and xmpRights:Marked.

The export now adds those three properties to the XMP packet after
the writer has written it, as it does for the modification date.
Marked is True for Copyrighted and False for Public Domain, and is left
out for Unknown. The notice and URL are escaped for XML, and characters
XML 1.0 does not allow are left out. A document without a copyright
gets none of the properties.

Docs: docs/mcp.md (File Info), docs/target-app-parity.md.

docs/mcp.md

@@ -2825,6 +2825,9 @@ author, description and keywords to the document info and XMP, PNG export writes
 creation date) as text chunks, and SVG export writes the description as `<desc>` and, with the `metadata` option,
 all of it as Dublin Core. PDF export and PDF-compatible `.ai` and `.ait` saves write the `created` date (the time of
 writing when the document has none) as the file's creation date and the time of writing as its modification date.
+They also write the `copyrightNotice` as `dc:rights`, the `copyrightUrl` as `xmpRights:WebStatement` and the
+`copyrightStatus` as `xmpRights:Marked` (`True` for copyrighted, `False` for public domain, none for unknown) to the
+XMP packet.
 A PDF, `.ai` or `.ait` opened from its pages or its editing copy (`document.open`,
 `file.newFromTemplate`, `file.revert`; not one restored from the document it carries) opens with the `author`,
 `description`, `keywords`, `copyrightStatus`, `copyrightNotice`, `copyrightUrl`, `created` and `modified` that its XMP

docs/target-app-parity.md

@@ -804,6 +804,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   - Desktop print transport uses `craft-print` for CUPS and modern Windows. Sheet composition, copies, separations and colour management remain in VectorCraft; Windows 7 retains WMI and the installed PDF viewer. The Print dialog's Media list also carries the Japanese papers — JIS B4 257 × 364 mm, JIS B5 182 × 257 mm and JIS B6 128 × 182 mm beside the ISO B4/B5 (250 × 353 and 176 × 250 mm, kept so settings and presets saved before them keep their paper), and はがき 100 × 148 mm, 往復はがき 148 × 200 mm, 封筒 長形3号 120 × 235 mm, 長形4号 90 × 225 mm, 角形2号 240 × 332 mm, 角形3号 216 × 277 mm and 四六判 127 × 188 mm; the JSON id or the dialog label names a paper, any case and spacing (`B5 (JIS)` or `b5jis`) (`crates/pdf/src/print/settings.rs`, `crates/pdf/src/tests_print.rs`). The print-preview and physical-device fidelity gaps remain, so print scores and hours are unchanged.
   - A PDF, PDF-compatible `.ai` or `.ait` opened from its pages or its editing copy opens with the File Info that its XMP packet and its document information dictionary give: the author, description, keywords, copyright status, notice and URL, and the created and modified dates, the XMP packet's value where both give one; the title is not changed (`crates/pdf/src/tests_file_info.rs`, `crates/engine/src/tests_fileinfo.rs`).
   - PDF export and PDF-compatible `.ai` and `.ait` saves write the document's File Info created date as the file's creation date, or the time of writing when the document has none, and the time of writing as its modification date; the page information mark still prints the time of writing (`crates/engine/src/tests_fileinfo.rs`, `crates/pdf/src/tests.rs`, `crates/pdf/src/tests_marks.rs`).
+  - PDF export and PDF-compatible `.ai` and `.ait` saves write File Info's copyright notice, URL and status to the XMP packet (`dc:rights`, `xmpRights:WebStatement`, `xmpRights:Marked`), so a PDF or `.ai` opened from its pages keeps them (`crates/pdf/src/tests_file_info.rs`, `crates/engine/src/tests_fileinfo.rs`).
   - Opening a PDF or PDF-compatible `.ai` whose XMP packet nests elements more than 256 deep no longer overflows the stack: File Info leaves the packet out and takes the document information dictionary's values (`crates/pdf/src/tests_file_info.rs`).
   - `file.print`, `print.preview` and `print.setup` take a print preset by name (`preset`: `[Default]` or a saved preset, in any case): its settings are used instead of the document's, with `settings` over them, `print.setup` saves them with the document, and an unknown name is refused with the list of presets.
   - Place and the Links panel, Package (placed `.vectorcraft` documents packaged with their own linked files and fonts, relinked to the copies: #777), File Info, Print with print presets, PostScript output and print tiling, slices and Save for Web, Export for Screens and Asset Export, CSS Properties, PNG/PDF/SVG/text clipboard flavours; files copied in a file manager paste as art (SVG, PDF, EMF/WMF, bitmaps) on every desktop platform, and Linux/Wayland reads the compositor's clipboard (#398); on Linux the Paste menu checks the clipboard off the UI thread, so an X11 owner that never answers can't freeze the window (#510); screenshots and other copied pictures paste as embedded images at the view centre everywhere, the web included (#457).