Canvas · Tools: select, move and snap, resize, draw, pen, text, brush

ToolLayer lies over an InfiniteCanvas and carries its tools. Select
takes the topmost shape a press reaches, Shift adds or drops one, a
drag moves the selection and snaps its nearest edge or middle to
another shape's within reach, a handle resizes it, Shift keeping a
corner's shape, and a drag on empty space draws a SelectionBox that
takes what lies wholly inside. The shape tools draw by a drag toward
any corner, Shift keeping them square; the pen adds a point per press
and a double press ends the path; text drops a line where pressed; the
brush strokes a path its width. A drag may end in the layer or out of
it; each gesture ends once and asks the owner. SelectionBox,
TransformHandles and SnapIndicator draw the marks.

ToolPalette picks a tool from icons named in tips; BrushSettings sets a
brush's width and hue; HistoryPanel lists the steps done, the undone
ones quiet, and takes the drawing to a step on Enter or a double press.

The model changes: lines and arrows end at a named corner, so they run
either way, and paths carry their width. Three Lucide icons: hexagon,
slash and move-up-right.

src/primitives/icon.rs

@@ -174,6 +174,7 @@ icons! {
     Heading3 => "heading-3",
     Headphones => "headphones",
     Heart => "heart",
+    Hexagon => "hexagon",
     History => "history",
     Hourglass => "hourglass",
     House => "house",
@@ -218,6 +219,7 @@ icons! {
     Moon => "moon",
     MousePointer2 => "mouse-pointer-2",
     Move => "move",
+    MoveUpRight => "move-up-right",
     Music => "music",
     Network => "network",
     NotebookPen => "notebook-pen",
@@ -271,6 +273,7 @@ icons! {
     Shuffle => "shuffle",
     SkipBack => "skip-back",
     SkipForward => "skip-forward",
+    Slash => "slash",
     SlidersHorizontal => "sliders-horizontal",
     Smartphone => "smartphone",
     Smile => "smile",