Handle buffer diff base updates and file renames properly for SSH projects (#14989)

Release Notes:

- N/A

---------

Co-authored-by: Conrad <conrad@zed.dev>

crates/assistant/src/slash_command/file_command.rs

@@ -188,7 +188,7 @@ fn collect_files(
     let project_handle = project.downgrade();
     let snapshots = project
         .read(cx)
-        .worktrees()
+        .worktrees(cx)
         .map(|worktree| worktree.read(cx).snapshot())
         .collect::<Vec<_>>();
     cx.spawn(|mut cx| async move {