Part of #2345: a marquee does not select a clip group by its hidden art

A marquee measured a clip group, and the objects on a layer with a
clipping mask, by all of their art, including the art the mask hides.
A marquee around a rectangle drawn next to a clip group also selected
the group when it crossed the group's hidden art. A click already
counts only the art inside the clipping path.

The marquee now takes a clip group, or an object on a clipping layer
or sublayer, only when it meets the area inside the clipping path, and
it measures the art there within that area's bounds. The same rule
applies to the objects that Direct and Group Selection select whole,
to Group Selection's E marquee, and in isolation mode when the clip
group or clipping layer itself, or one object directly inside it, is
isolated. The anchor points that Direct Selection's marquee picks are
unchanged.

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

docs/target-app-parity.md

@@ -487,6 +487,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   - **Shaper:** uneven squares and rectangles become live rectangles even when drawing begins mid-edge. Recognition uses uniformly spaced samples and closed-loop corners, fits rectangle edges/angles rather than requiring a nearly perfect bounding-box fill, and includes the pointer-release position. Rectangles/squares and ellipses snap to 45° steps, hexagons to 90°, and triangles point up or down; lines keep their free angle even with Shift. Shaper Groups retain the live originals, merge regions with the gesture-origin fill, punch fills independently from strokes, remove boundaries on exiting scribbles and trim protruding stroke pieces. Source moves/resizes re-evaluate the result in the same undo step; double-click enters construction editing, and with the Shaper or Selection tool a click on the arrow widget beside a Shaper Group's original shapes switches the group between Face Selection and Construction mode. Native save/reopen, face recoloring, Release and Expand are covered. Finer gesture heuristics remain.
   - **Selection:** Selection, Direct/Group Selection, Magic Wand, Lasso. A Shift-drag marquee toggles what it reaches: objects with the Selection tool, anchors with Direct and Group Selection (#483); the Lasso adds with Shift and subtracts with Alt. Dragging a path segment with Direct Selection bends it when it's curved (its anchors stay) and moves its two anchors when it's straight, one undo step; the fill, Shift or Alt still pick the whole path (Alt-drag copies it).
     With the Selection or Group Selection tool, pressing E while dragging a marquee makes the marquee select only the objects that lie entirely inside it. Pressing E again switches the marquee back to its default selection.
+    A marquee selects a clip group, or an object on a layer with a clipping mask, only when it reaches the area inside the clipping path, and it measures the art only within that path's bounds. Within the bounds of a mask that is not a rectangle, it can still select art that the mask hides. Direct Selection's marquee still selects the hidden anchor points inside it (#2345).
     A key object needs another selected object outside it. A Shift-click or any other change that leaves one object selected clears the key, and `select.key` sets none on one object or on a group selected with only its own members. With one object selected, the Align panel, the Control bar and the Properties panel align it to the artboard whatever Align To is set to.
     With two or more objects selected and no key object, Align to Key Object makes the topmost of them the key, whatever order they were selected in, and the Align panel, the Control bar and the Properties panel align to it. Align To keeps its Selection or Artboard choice and shows it again once the key is cleared.
     Object › Align aligns objects as the align buttons do: it aligns one object to the active artboard whatever Align To is set to, and otherwise it aligns to the key object while there is one, else to the Align To choice, which is saved with the preferences (`ui.inspect` → `ui.align_to`). With direct-selected anchor points, Object › Align aligns the points to their own bounds. While one object is selected, Align To shows Artboard.