Hide backups of earlier guests that reused the VMID

Proxmox ties backups to the VMID only, so a deleted guest's backups
were listed under the new guest with that VMID. CT 104 showed planka
backups next to debian's, and VM 108 showed vaultwarden backups.

Backups whose notes name another guest are now hidden by default. The
notes come from the job's {{guestname}}, so "debian (manual)" still
counts as debian. A line says how many are hidden, and the a key shows
them, marked "(earlier guest)". Backups without notes are always
shown.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -20,7 +20,7 @@ uv run cv4pve-tui
 | `x` | stop - hard power-off (confirm) |
 | `r` | reboot (confirm) |
 | `e` | edit cores / memory / grow a disk (disk growth asks again; it cannot be undone) |
-| `i` | info: backups, backup job, network (config and runtime IPs); `b` there = backup now (snapshot, zstd, storage choice) |
+| `i` | info: backups, backup job, network (config and runtime IPs); `b` there = backup now (snapshot, zstd, storage choice); `a` there = also show backups of earlier guests that had the same VMID |
 | `t` | shell in a running LXC container (`ssh -t root@<node> pct enter <vmid>`) |
 | `g` | refresh |
 | `c` | switch cv4pve-cli context (cluster) |