fix(code-server): pass SERVICE_HOSTNAME as HOST so the zsh prompt shows the hostname

code-server/.env.example

@@ -10,6 +10,6 @@ PASSWORD=
 GIT_NAME=
 GIT_EMAIL=
 
-# Container hostname, shown in the shell prompt.
+# Container hostname, also passed in as HOST -- the name zsh's prompt shows.
 # Not named HOSTNAME: the deploying shell's own HOSTNAME would override it.
 SERVICE_HOSTNAME=code-server