chore: make webfs usable

src/shell/Shell.ts

@@ -1,3 +1,4 @@
+import type { Item } from '../fs/Item'
 import type { Program } from '../program/Program'
 import type { Terminal } from '../terminal/Terminal'
 import type { EventBroadcaster } from '../utils/EventBroadcaster'
@@ -17,4 +18,5 @@ export abstract class Shell {
     abstract ExecuteProgram(name: string, args: string[]): void
     abstract Init(): Promise<void>
     abstract HandleKeyInput(key: string, isCharacter: boolean): void
+    abstract SetWorkingDirectory(directory: Item): Promise<void>
 }