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>

docs/control-protocol.md

@@ -24,6 +24,7 @@ so only enable it while you use it. Transport: `apps/vectorcraft/src/control_ser
 | `ui.tool.select` / `ui.tool.list` | `{tool}` | |
 | `ui.pointer` | `{events:[{kind: down|drag|up|move|doubleclick, x, y, space?: "doc"|"screen", mods?}]}` | drive the active tool exactly like the mouse |
 | `ui.key` / `ui.text` | `{key, shift?, alt?, cmd?}` / `{text}` | synthetic keyboard input |
+| `ui.wheel` | `{x, y, dy?, dx?, unit?: "line"\|"point", shift?, alt?, cmd?}` | a mouse wheel turn over screen point (x, y): `dy` notches up (+) or down, `dx` sideways. Over the canvas the wheel scrolls and Cmd- or Alt-wheel zooms; with the `zoomWithMouseWheel` preference the wheel zooms about the pointer, Shift-wheel scrolls up and down and Cmd-wheel (Ctrl on Windows and Linux) sideways |
 | `ui.set` | `{brightness?, panel?, rulers?, outline?, grid?, smartGuides?, boundingBox?, controlBar?}` | |
 | `ui.dialog.set` / `.confirm` / `.cancel` | `{field, value}` | fill and submit the open dialog |
 | `ui.screenshot` | `{path?}` | capture the window (PNG). Needs a presented frame: with the screen locked or the window minimized/covered it fails after ~8 s with an explanatory error |
@@ -462,7 +463,7 @@ from)}` opens too: dialog `printPreset`, the Print dialog's settings fields plus
 Export… are `print.presets.delete`, `print.presets.import` and `print.presets.export`; `ui.dialog.confirm` closes.
 Opening a `.vcprintpresets` file with `app.open` imports its presets.
 
-Modifiers on synthetic input: `ui.key`, `ui.click` and `ui.drag` take `shift`, `alt`, `ctrl` and `cmd` (Command on
+Modifiers on synthetic input: `ui.key`, `ui.click`, `ui.drag` and `ui.wheel` take `shift`, `alt`, `ctrl` and `cmd` (Command on
 macOS, Ctrl elsewhere), and the app holds them for the frames the input spans, as if the keys were down: a key's
 press, its `text` and its release; a click's press and release; a drag from the press through every move to the
 release. Every handler sees them (Shift+arrow nudges by the big increment, Alt+arrow nudges a copy, Shift-clicking a

docs/mcp.md

@@ -1072,6 +1072,29 @@ Effects off a 100 pt wide rectangle with a 10 pt stroke set to `width: 220` gets
 {"name":"run_command","arguments":{"command":"object.align","params":{"horizontal":"left","bounds":"preview"}}}
 ```
 
+## Selection preferences
+
+The Selection & Anchor Display and General preferences apply to `pointer_gesture` as they do to the mouse:
+
+- `selectionTolerance` (1–8 px, 3 by default): how near a click must be to a path to pick it, and to an anchor or
+  handle for Direct Selection.
+- `objectSelectionByPathOnly`: a click inside a filled path or compound path doesn't select it, one on its path does.
+- `ctrlClickSelectsBehind` (on by default): a Selection tool click with `mods: {cmd: true}` (Command on macOS, Ctrl
+  elsewhere) selects the object under the selected one there, the next such click the one under that, then the
+  topmost again. Cmd held to borrow the selection tool from another tool clicks as usual.
+- `doubleClickToIsolate` (on by default): off, a `doubleclick` on a group with the Selection tool no longer isolates it.
+- `usePreciseCursors`: the Pen, Eyedropper, Slice and Blend tools' pointers are a crosshair.
+
+```json
+{"name":"run_command","arguments":{"command":"prefs.set","params":{"key":"objectSelectionByPathOnly","value":true}}}
+{"name":"pointer_gesture","arguments":{"tool":"selection","mods":{"cmd":true},"events":[{"kind":"down","x":175,"y":125},{"kind":"up","x":175,"y":125}]}}
+```
+
+The preferences for the view need the desktop app (`vectorcraft-cli mcp --connect`): `zoomWithMouseWheel` (the
+wheel zooms about the pointer, Shift-wheel scrolls up and down, Cmd/Ctrl-wheel sideways; the control channel's
+`ui.wheel` turns the wheel), `zoomToSelection` (on: Zoom In and Zoom Out centre the selection), `showToolTips`,
+`anchorSize` (1–7), `gridColor`, `gridStyle`, `gridsInBack`, `guideColor`, `guideStyle` and `recentFontsCount`.
+
 ## Width points
 
 `stroke.widthPoint.set {id, t, left, right, index?, adjustAdjoining?}` adds a width point (side widths in points) or,