Add Tool base class

frontend/src/tools/Tool.ts

@@ -0,0 +1,16 @@
+import { YjsDocument } from '../crdt/YjsDocument';
+xport abstract class Tool {
+  protected yjsDoc: YjsDocument;
+  protected name: string;
+
+  constructor(yjsDoc: YjsDocument) {
+    this.yjsDoc = yjsDoc;
+    this.name = '';
+  }
+
+  abstract onMouseDown(event: MouseEvent): void;
+  abstract onMouseMove(event: MouseEvent): void;
+  abstract onMouseUp(event: MouseEvent): void;
+  abstract onKeyUp(event: KeyboardEvent): void;
+  abstract reset(): void;
+}