Park the pre-merge droplet installer in attic/ as a rollback path

The unified services/asterisk.sh has not been run on real hardware yet, so
keep the previous services/asterisk-digital-ocean.sh available verbatim until
it has. attic/ sits outside setup.sh's services/*.sh glob, so the copy never
self-registers, never appears in the menu, and only runs if invoked directly
(it kept its own standalone bootstrap: sudo bash attic/asterisk-digital-ocean.sh).

Both scripts agree on where an existing droplet install lives
(~/docker/asterisk-digital-ocean, easy-asterisk-do containers), so moving
between them doesn't relocate anything.

attic/README.md is explicit that this is a way to get the old installer back,
not an undo button — what actually protects an existing install is --dry-run,
choosing update/cancel over fresh at the reinstall prompt, and a snapshot —
and that the copy should be deleted once the merge is confirmed, since two
copies of the same logic is the problem the merge removed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NAddJGE1G6eGaPzmScG5Vh

CLAUDE.md

@@ -56,6 +56,14 @@ Firewall — behind that one answer. Two lessons worth reusing:
   silently empty on every home/LAN install as a result. Both now apply
   everywhere.
 
+The pre-merge installer is parked at `attic/asterisk-digital-ocean.sh` as a
+rollback path until the unified one is confirmed on real hardware. `attic/`
+is outside `setup.sh`'s `services/*.sh` glob, so nothing there registers or
+runs on its own — see `attic/README.md`, including why it's a way to get the
+old script back rather than an undo button. Delete it once the merge is
+proven; a second copy of the same logic is what the merge existed to remove,
+and fixes are deliberately not backported into it.
+
 ## Minimal Docker service template
 
 ```bash