feat: add chroma key tool and settings, including UI components and controls

view/ToolOverlay.tsx

@@ -1,4 +1,4 @@
-import { Cursor, Eraser, Hand, PaintBrush } from "@phosphor-icons/react";
+import { Cursor, Eraser, Hand, PaintBrush, DropHalf } from "@phosphor-icons/react";
 import { commandIds } from "@commands/ids";
 import type { AppStore } from "@editor/store";
 import type { InteractionMode, ToolId } from "@editor/tools";
@@ -45,6 +45,8 @@ function iconForTool(tool: ToolId) {
       return PaintBrush;
     case "eraser":
       return Eraser;
+    case "chromaKey":
+      return DropHalf;
     case "pan":
       return Hand;
     case "select":