feat(FN-4684): complete Step 3 — add selector surface and audit types

Fusion-Task-Id: FN-4684
Fusion-Task-Lineage: 142e512b-8189-4029-9df4-4bd40b69ed2a

packages/engine/src/worktree-pool.ts

@@ -7,6 +7,15 @@ import { assertCleanBranchAtBase, inspectBranchConflict } from "./branch-conflic
 import { worktreePoolLog } from "./logger.js";
 import { isInsideConfiguredWorktreesDir, resolveWorktreesDir } from "./worktree-paths.js";
 
+export {
+  type WorktreeBackend,
+  type WorktreeBackendKind,
+  NativeWorktreeBackend,
+  WorktrunkWorktreeBackend,
+  WorktrunkOperationError,
+  resolveWorktreeBackend,
+} from "./worktree-backend.js";
+
 const execAsync = promisify(exec);
 
 export function canonicalizePath(path: string): string {