feat(tools): add brush raster painting

view/ToolOverlay.tsx

@@ -1,4 +1,4 @@
-import { Crop, Cursor, Hand } from "@phosphor-icons/react";
+import { Crop, Cursor, Hand, PaintBrush } from "@phosphor-icons/react";
 import { commandIds } from "@commands/ids";
 import type { AppStore } from "@editor/store";
 import type { InteractionMode, ToolId } from "@editor/tools";
@@ -43,6 +43,8 @@ function iconForTool(tool: ToolId) {
   switch (tool) {
     case "crop":
       return Crop;
+    case "brush":
+      return PaintBrush;
     case "pan":
       return Hand;
     case "select":