fix(worktrees): remove worktrees in the background (#3319)

* refactor(worktrees): fetch source once during creation

* fix(worktrees): remove worktrees in background

* fix(worktrees): show background removal progress

* fix(worktrees): name the worktree in removal toasts

packages/ui/src/lib/api/types.ts

@@ -438,6 +438,7 @@ export interface GitWorktreeCreateResult {
   path: string;
   directoryCreated?: true;
   bootstrapStatus?: GitWorktreeBootstrapStatus;
+  sourceFetchFailed?: true;
 }
 
 export interface RemoveGitWorktreePayload {