Fix #593: anchors and handle ends are easier to grab than the segments through them

An anchor was picked within the selection tolerance (3 px), the same reach
as its segments: a press a little off the anchor's 5 px square took the
curve instead.

- `ToolContext::point_tol`: anchors and direction handle ends are picked
  within the selection tolerance, but at least 2 px past the drawn point
  (4.5 px at the default Size 3, more with a larger Size). Anchors are
  tested before segments, so where both are within reach the anchor wins.
- Direct Selection (presses, Highlight anchors on mouse over, blend spine
  points and handles), the Anchor Point, Delete Anchor Point and Scissors
  tools, and the Pen (its Alt conversions; its close/continue reach stays
  5 px unless the points are drawn larger) use it. Segments, objects and
  frame edges keep the selection tolerance.
- Of the topmost path with anchors in reach, the nearest anchor is picked.

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

crates/engine/src/tooling.rs

@@ -205,6 +205,7 @@ impl Session {
             slices_locked: self.menu.slices_locked,
             auto_add_delete: !self.prefs.disable_auto_add_delete,
             selection_tolerance: self.prefs.selection_tolerance,
+            anchor_size: self.prefs.anchor_size,
             path_only: self.prefs.object_selection_by_path_only,
             type_path_only: self.prefs.type_selection_by_path_only,
             double_click_isolate: self.prefs.double_click_to_isolate,