Docs: Additional Plug-ins Folder's Choose… cites the preferences help

The progress line for the folder preferences now cites the preferences
help for Plug-ins & Scratch Disks as the place where additional plug-ins
folders are set, and names the plug-ins Choose… button and the check of
a typed folder on OK as VectorCraft's own rules.

docs/target-app-parity.md

@@ -1144,7 +1144,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
     PDF export writes a linear or radial gradient that mixes a spot color with process colors, or two spot colors, as a DeviceN shading of the spot inks and the process inks its stops use, so each spot ink prints on its own plate; an off-center midpoint is written as a stop with the inks halfway between its two stops. A gradient that mixes a spot color with RGB or Lab colors is still written without the spot ink, with a warning. A Perceptual gradient of spot inks is written as a Separation or DeviceN shading of the stops on its curve; a dithered gradient fill, and a Perceptual gradient with RGB or Lab stops other than white or more than 4,096 stops on its curve, are written as images in process colors, with a warning. A Lab spot color in such a shading is named by the same Separation space, with the Lab alternate, as its flat fills (`engine/src/tests/linked_stops.rs`, `engine/src/tests/labspots.rs`).
     PDF export writes a spot color named All or None (in a Separation space, the names of every plate and of no plate: [ISO 32000-1:2008](https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008.pdf), 8.6.6.4) as the ink All Spot or None Spot (All Spot 2 and on when a spot swatch already has that name) in its fills, strokes, gradients, colorized images and Lab alternates; Registration still prints on every plate (`pdf/src/tests/output.rs`).
   - `.vectorcraft` (lossless JSON, compressed, atomic saves, save down to v1), Save As with a format chooser, Save a Copy, Revert, templates, Data Recovery after a crash (browser tabs hold their copies with Web Locks too, so a background tab's copies are never taken for a crash's, and a tab repairs copies another removed when it resumes: #367), background save and export. The desktop app writes its warnings and errors (graphics adapter, a lost graphics device, panics the guard recovered from) to standard error and to `logs/vectorcraft.log` next to the preferences, the two previous runs kept and each file capped at 16 MiB, so a launch without a terminal still leaves something to attach to a bug report (#465). Native documents with a lot of path data (traced or generated art, in layers, symbols or patterns) are saved as compact JSON, about a fifth of the size; small documents stay pretty-printed (#1492). Saving to a network drive on macOS falls back to a plain fsync when the share refuses a full flush (#1625, part of #1620; not confirmed on a real share), and a save still succeeds when a folder refuses the temporary file, the rename over the document or copying permissions: the content is written elsewhere first and copied in, and a failed copy keeps the temporary file and names it (#1649, part of #1620). A document opened by a relative path finds its relatively linked images, and `vectorcraft-cli convert` lists what reading the input left out as `importWarnings` (#1606, fixes #1604).
-    Preferences › File Handling › Data Recovery › Folder has a Choose… button on the desktop that picks the folder Data Recovery keeps its copies in ([Illustrator reference, Set Data Recovery preferences](https://web.archive.org/web/20210601162814/https://helpx.adobe.com/pdf/illustrator_reference.pdf)); a picked folder that Data Recovery cannot create its folders in or list is refused with a status message, and the field keeps its value. OK applies the same check to a folder typed into the field: when it fails, the dialog stays open, the status bar says why and no preference changes; an empty field (the default folder) and the folder already saved are not checked. Preferences › Plug-ins & Scratch Disks › Additional Plug-ins Folder has a Choose… button on the desktop too ([an answer describing Additional Plug-ins Folder's Choose button](https://stackoverflow.com/questions/43902576/how-to-make-adobe-illustrator-use-a-plug-in-built-in-xcode)); VectorCraft's own rule refuses a picked or typed folder whose contents can't be listed. Additional Fonts Folder and Templates Folder stay typed only.
+    Preferences › File Handling › Data Recovery › Folder has a Choose… button on the desktop that picks the folder Data Recovery keeps its copies in ([Illustrator reference, Set Data Recovery preferences](https://web.archive.org/web/20210601162814/https://helpx.adobe.com/pdf/illustrator_reference.pdf)); a picked folder that Data Recovery cannot create its folders in or list is refused with a status message, and the field keeps its value. OK applies the same check to a folder typed into the field (VectorCraft's own rule): when it fails, the dialog stays open, the status bar says why and no preference changes; an empty field (the default folder) and the folder already saved are not checked. Preferences › Plug-ins & Scratch Disks is where additional plug-ins folders are set ([Illustrator preferences help](https://helpx.adobe.com/illustrator/desktop/get-started/preferences-and-settings/set-app-preferences.html)); its Additional Plug-ins Folder has a Choose… button on the desktop as well, VectorCraft's own, matching Data Recovery's, and VectorCraft's own rule refuses a picked or typed folder whose contents can't be listed. Additional Fonts Folder and Templates Folder stay typed only.
     A name typed in the desktop save panel without the file type's extension gets it, and when a file of that name exists, which the panel did not ask about, Save, Save As, Save a Copy, Save as Template, the exports and every other write through a save panel ask before replacing it (dialog `replaceFile`; Cancel writes nothing).
     A name returned by the desktop save panel with the extension of a format the save does not write has it replaced with the saved format's: Save As of a new document saves `card.ait` and `card.png` as `card.vectorcraft`, and Save as Template saves `card.pdf` as `card.vctemplate`. An extension that names no format stays part of the name (`notes.v2` is saved as `notes.v2.vectorcraft`).
     Export As, Save as PDF, Save for Office Documents, Save for Web, Text Export Options, print to file, the presets' Export… and the library, swatch and Document Info saves replace a typed extension of another format than the one they write in the same way: Export As PNG writes `card.svg` as `card.png`, Save as PDF writes `card.png` as `card.pdf`, and `document.exportSelection` with a `format` suggests and adds that format's extension. An extension of the written format stays as typed in any letter case (`photo.JPEG` for JPEG), Export As SVG writes `art.svgz` compressed, and `document.exportSelection` without a `format` writes the format the typed extension names (`tests/saveext.rs`).