Part of #394: Preferences that act on selection, the wheel, tool tips and the grid

Fifteen Preferences options were stored but read by nothing. They now act,
through the existing plumbing (ToolContext for the tools, the prefs read by the
canvas for the view), and reach agents through prefs.set:

- General: Show Tool Tips (off: no widget's tool tip comes due), Double Click
  To Isolate, Zoom with Mouse Wheel (the wheel zooms about the pointer,
  Shift-wheel scrolls up and down, Cmd/Ctrl-wheel sideways), Use Precise
  Cursors (Pen, Eyedropper, Slice and Blend pointers become a crosshair).
- Selection & Anchor Display: Tolerance (objects, anchors and handles, in
  place of the fixed 3 and 4 px), Object Selection by Path Only (compound
  paths too), Command Click to Select Objects Behind (cycles down the objects
  under the pointer; not when Cmd only borrows the selection tool), Zoom to
  Selection (Zoom In/Out centre the selection), anchor Size, Highlight anchors
  on mouse over (Direct Selection).
- Type: Number of Recent Fonts (up to 15 Recent Fonts slots).
- Guides & Grid: guide and grid Color and Style (lines or dots), Grids In Back.

The canvas's context menu, panel drops and hover highlight pick objects like
the selection tools. The control channel gets ui.wheel (with modifiers held
like ui.click) so agents can turn the wheel. The rest of #394 stays open.

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

crates/engine/src/tooling.rs

@@ -152,6 +152,11 @@ impl Session {
             slices_hidden: self.menu.slices_hidden,
             slices_locked: self.menu.slices_locked,
             auto_add_delete: !self.prefs.disable_auto_add_delete,
+            selection_tolerance: self.prefs.selection_tolerance,
+            path_only: self.prefs.object_selection_by_path_only,
+            double_click_isolate: self.prefs.double_click_to_isolate,
+            select_behind: self.prefs.ctrl_click_selects_behind,
+            highlight_anchors: self.prefs.highlight_anchors_on_hover,
             screen: view.screen,
             plane_widget: self.prefs.perspective_widget.show.then_some(self.prefs.perspective_widget.position),
         };
@@ -265,8 +270,11 @@ impl Session {
         v
     }
 
+    /// The pointer the active tool shows at `p` (General › Use Precise Cursors makes the drawing
+    /// tools' a crosshair, [`Cursor::precise`]).
     pub fn cursor(&mut self, p: Point, mods: Mods, view: ViewInfo) -> Cursor {
-        self.with_tool_cx(view, |t, cx| t.cursor(cx, p, mods))
+        let c = self.with_tool_cx(view, |t, cx| t.cursor(cx, p, mods));
+        if self.prefs.use_precise_cursors { c.precise() } else { c }
     }
 
     pub fn tool_options(&self) -> Value {