Persist zoxide directory history across container recreations

Zoxide stores its database at ~/.local/share/zoxide/db.zo. Without a
named volume, the 'z <fragment>' jump targets are lost on every
'docker compose up --force-recreate'.

Add devbox-zoxide named volume in docker-compose.yml and
docker-compose.shared.yml, add ~/.local/share/zoxide to the
entrypoint ownership-fix loop per AGENTS.md convention, and update
the data-persistence tables in README.md and DOCKER_HUB.md.

docker-compose.yml

@@ -61,6 +61,9 @@ services:
       # Without this, ~/.bash_history is lost on 'docker compose up --force-recreate'.
       - devbox-shell-history:/home/developer/.cache/bash
 
+      # Persist zoxide directory history ('z <fragment>' to jump).
+      - devbox-zoxide:/home/developer/.local/share/zoxide
+
       # Optional: override baked shell defaults with your host's rc files.
       # The image ships sensible defaults (history tuning, prefix-search on
       # Up/Down arrows, fzf/zoxide integration). Uncomment to use your own:
@@ -93,6 +96,7 @@ volumes:
   devbox-data:
   devbox-state:
   devbox-shell-history:
+  devbox-zoxide:
   devbox-uv:
   # devbox-rustup:
   # devbox-cargo: