M4.55: File Info with author, description, keyword chips, rating and copyright, written to SVG, PDF and PNG

file.info takes and reports the title, author, author title, description,
keywords, rating, copyright status, notice and URL in one undo step, plus
the read-only created (file.new) and modified (every save to a file) dates;
junk values are refused. Document.metadata (DocMetadata) round-trips
natively. PDF export writes author, subject and keywords to the info
dictionary and XMP, PNG export writes tEXt/iTXt chunks, SVG export writes
<desc> and, with the metadata option, every field as Dublin Core. The File
Info dialog (fileInfo, ui.fileInfoDialog) edits it with keyword chips and
star ratings.

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

docs/control-protocol.md

@@ -239,3 +239,10 @@ paste at the centre of the view. The Paste menu items are enabled while the syst
 nothing copied in the app (looked at up to four times a second; `ui.menu.list` shows it). The Layers panel menu (≡ on
 the dock's tab strip while Layers shows) lists the layer commands and Paste Remembers Layers
 (`layer.pasteRemembersLayers`, checked when on).
+
+File Info: File → File Info… (`file.info` from the menu or Cmd+Alt+Shift+I; `ui.fileInfoDialog` for agents) opens the
+`fileInfo` dialog. Its fields are what `file.info` reports (`title`, `author`, `authorTitle`, `description`,
+`keywords` (a list: the chips), `rating`, `copyrightStatus`, `copyrightNotice`, `copyrightUrl`; `created` and
+`modified` are shown read-only) plus `__keyword`, keywords typed but not added yet (comma-separated; OK adds them).
+`ui.dialog.confirm` runs `file.info` with them as one undo step; a bad value answers with an error and the dialog
+stays open.