Part of #2460: a huge selection of type, images, symbols or meshes shows its bounds

A selection with more than 100,000 anchors shows its bounds instead of
every outline and anchor (#525). The count took in path anchors only.
Type, images, symbol instances, placed documents, gradient meshes and
envelopes counted nothing, although the selection overlay outlines each
of them: a box, an area type frame or a type path, a baseline marker
for point type, and the points and mesh lines of meshes and envelopes.
The PDF importer makes type objects from a page's text lines, one image
object per image and one gradient mesh per patch or triangle of a mesh
shading, so selecting all of a large PDF outlined each of them: 131,072
selected mesh pieces need 16.8 million vertices, a 336 MB vertex
buffer, past wgpu's 256 MiB buffer limit.

The count now takes in what the overlay draws for each kind. Paths
count their anchors. Area type and type on a path count the anchors of
their frame or path, and point type counts six: its box's corners and
the ends of its baseline marker. Images, symbol instances, placed
documents, and area type or type on a path in perspective count the
four corners of their box, and gradient meshes and envelopes count
their points and the ends of their mesh lines. The selection's outline,
the key object's outline and the hover highlight all use the count.

Docs: docs/target-app-parity.md.

docs/target-app-parity.md

@@ -703,6 +703,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   The Pathfinder panel, Offset Path, Clean Up, Divide Objects Below, Make and Release Blend, Envelope Distort's Make and Release, Repeat (Radial, Grid, Mirror and Release), Vector Halftone, New and Redefine Symbol, Delete Symbol, erasing with the Symbol Sprayer, Rasterize, Convert to Artboards, Flatten Transparency, Clear Guides, Shape Builder, Live Paint, Release Image Trace, Make and Release Opacity Mask, Delete with direct-selected anchor points, Remove Anchor Points, Cut Path, and the Shaper, Knife, Eraser, Path Eraser, Line Cut, Rectangle Cut, Mirror & Cut and Blob Brush tools add and remove objects in one pass over each layer or group they change, and Outline Stroke and Expand write each new object in the place of the object it replaces (#1429).
   With more than 10,000 type on a path objects selected, the Selection and Direct Selection tools neither draw nor hit-test the objects' brackets.
   Type › Show Hidden Characters keeps the marks it places on each text object from one frame to the next. The canvas lays a text object out again when an edit changes it or its threaded story, or when the last frame that showed the marks did not draw it, and it lays out all type in view again when the fonts or the hyphenation exceptions change. With 1,000 two-line labels in view, drawing the marks takes 0.8 ms per frame in a release build instead of 19.7 ms.
+  A selection with more than 100,000 points to outline shows its bounds instead of each object's outline and anchors. Paths count their anchors. Area type and type on a path count the anchors of their frame or path, and point type counts six: its box's corners and the ends of its baseline marker. Images, symbol instances, placed documents, and area type or type on a path in perspective count the four corners of their box, and gradient meshes and envelopes count their points and the ends of their mesh lines. The hover highlight leaves out an object past that count, and such an object shows its bounds as the key object. With 32,768 type objects, images, symbol instances, gradient meshes or envelopes selected, the selection's outlines and anchors add fewer than 100 vertices to the canvas's mesh (#2460).
   Delete, Cut, Group, Ungroup, Make and Release Compound Path, Make Clipping Mask, Send to Current Layer, Duplicate, Copy in the Move, Rotate, Scale, Reflect and Shear dialogs, Transform Each with Copy and each move of an Alt-drag take time in proportion to the size of the document (#1429).
   In the web build the status bar's render and UI times are measured with the browser's `performance.now()`, and the Layers panel stops rendering row thumbnails in a frame once they have taken 8 ms.
   An Alt-drag with the Selection, Direct Selection, Group Selection, Rotate, Scale, Reflect or Shear tool copies the selection on its first move, and the moves after it transform those copies; the previews of the Move, Rotate, Scale, Reflect and Shear dialogs with Copy and Preview on copy the selection once in the same way (#1429).