Remove post-HM backups and document zzbubbles.sh cleanup

README.md

@@ -45,5 +45,9 @@ git push -u origin main
 - `sandbox = true` is a restricted setting; when supplied from the user-level
   config it is ignored with a warning (the daemon enforces it from
   `/etc/nix/nix.conf`). This is cosmetic.
-- Existing pre-Home-Manager dotfiles were moved to `~/.bashrc.backup` and
-  `~/.profile.backup` during the first switch.
+- Existing pre-Home-Manager dotfiles are no longer kept as backups; the shell is
+  fully owned by `programs.bash` + `programs.starship` (session vars from
+  `hm-session-vars.sh`).
+- `/etc/profile.d/zzbubbles.sh` is a stale, unmanaged start-of-day script that
+  duplicates starship init and references a removed `/home/runner` path. Remove
+  it once (sudo): `sudo rm /etc/profile.d/zzbubbles.sh`.