sh: Add distrobox alias and enable displaying host

Add a simple alias to quickly use distrobox with `db` alias, and modify
pure prompt initialization slightly so that it displays a hostname when
in a distrobox container (akin to operating from ssh or normal container
usage).

HACKY implementation makes use of both an internal pure prompt api
(see here https://github.com/sindresorhus/pure/issues/585)
and a distrobox env var that I am not sure how exposed it is either.
Powerlevel10k uses a similar method though, so maybe it is fine
(see here 33916e91a7/internal/p10k.zsh (L8336)).

sh/.config/sh/alias

@@ -119,3 +119,8 @@ elif exist ipython; then
 elif exist python; then
     alias py=python
 fi
+
+# distrobox
+if exist distrobox; then
+    alias db=distrobox
+fi

terminal/.config/zsh/.zshrc

@@ -66,6 +66,10 @@ promptinit
 prompt_newline='%666v'
 # show git stash status as a ≡
 zstyle :prompt:pure:git:stash show yes
+# show hostname if we are in a distrobox environment
+if [ -n "$DISTROBOX_ENTER_PATH" ] && [ -f /run/.containerenv ]; then
+    local container=lxc
+fi
 prompt pure
 
 # shellcheck source=alias