Replace the duplicate-host check with a live Proxmox query, drop deployedTargets

variables.nix's deployedTargets was a manually-maintained list with no
enforcement keeping it in sync with reality -- it caused two separate
false refusals in a row (naming a VM as deployed well after it had been
destroyed, then matching a target against itself once the list was
"corrected"). Static files can't track whether a resource still actually
exists.

create-proxmox-resource.sh's duplicate-host guard now queries the
Proxmox node directly (qm/pct's own name/hostname config, matched
against --host) instead. Also fixes a gap in that live check: it
originally swallowed ssh failures and would have silently treated "can't
reach the node" the same as "checked, nothing there" -- it now refuses
instead of guessing when the node can't be reached.

deployedTargets is removed entirely from variables.nix since nothing
else in the repo consumed it once this script no longer does; README.md's
Hosts table remains the sole source of truth for "(real, deployed)"
status. CLAUDE.md and the script's own --help/comments updated to match.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

CLAUDE.md

@@ -93,9 +93,10 @@ Beyond `codex-setup.sh`/`codex-maintenance.sh` above, `scripts/` also has:
   (`--force-rebuild` to skip that and always rebuild), and probes
   nix-cache's substituter/remote-builder reachability once up front rather
   than letting every `nix build` call retry against it individually.
-  Refuses to create a target whose host identity already has a real
-  deployment elsewhere (`variables.nix`'s `deployedTargets`) unless
-  `--allow-duplicate-host` is passed. `--dry-run` throughout both modes.
+  Refuses to create a target whose host identity already exists live on
+  the node (checked directly via `qm`/`pct`, not any file in this repo)
+  unless `--allow-duplicate-host` is passed. `--dry-run` throughout both
+  modes.
 - `scripts/env.sh` — shared config (`PROXMOX_HOST`, storage pool, bridge,
   default cores/memory) sourced by `create-proxmox-resource.sh`. Add new
   cross-script config here instead of duplicating it per-script.